AS2327.1 2003 CompositeStructures SimplySupport

AS 2327.1—2003

Australian Standard™

Composite structures

Part 1: Simply supported beams

AS

2327.1

This Australian Standard was prepared by Committee BD-032, Composite Construction. It was approved on behalf of the Council of Standards Australia on 3 June 2003 and published on 18 August 2003.

The following are represented on Committee BD-032:

Association of Consulting Engineers Australia

Australian Building Codes Board

Australian Steel Institute

Bureau of Steel Manufacturers of Australia

Institution of Engineers Australia

Steel Reinforcement Institute of Australia

University of New South Wales

University of Adelaide

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This Standard was issued in draft form for comment as DR 99100.

http://www.standards.com.au

AS 2327.1—2003

Australian Standard™



Originated as AS 1480 Supplement 1—1974. Previous edition AS 2327.1—1996. Third edition 2003.

COPYRIGHT

© Standards Australia International

All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher.

Published by Standards Australia International Ltd GPO Box 5420, Sydney, NSW 2001, Australia

ISBN 0 7337 5338 8

AS 2327.1—2003 2

PREFACE

This Standard was prepared by the Standards Australia Committee BD-032, Composite

Construction, to supersede AS 2327.1—1996 Composite structures in structural steel and

concrete, Part 1—Simply supported beams.

This revision incorporates a number of technical and editorial changes. The principal

differences are briefly outlined in the following:

1 Shear connectors:

(a) The value of the density reduction factor (kr), used in the calculation of the

design shear capacity (fds) of shear connectors with lightweight concrete, has

been changed to equal 1.0 for welded-studs (since the effect of lower concrete

density is already taken into account in the calculation of nominal shear

capacity (fvs) using Equation 8.3.2.1(2)), and a constant value of 0.8 for

channels and high-strength structural bolts.

(b) A procedure for calculating the nominal shear capacity (fvs) of channel or high-

strength structural bolt shear connectors during the initial part of Construction

Stage 5 when 15 ≤ f′cj < 20 MPa, previously omitted from AS 2327.1, has been

included, viz. at f′cj = 15 MPa, fvs equals 80% of the values given in Table 8.2

and Table 8.3 f′ c = 20 MPa, and linear interpolation is used for values of f′ cj

between 15 and 20 MPa.

(c) The Grade 300, 100 PFC (parallel flange channel) may now be used as a fully

equivalent shear connector to the Grade 250, 100 TFC (channel).

2 Open-rib and closed-rib profiles Distinction is made between open-rib and closed-

rib profile steel sheeting when designing the shear connection of the composite beam.

3 Welded stud locations Clause 8.4.2 clarifies that when automatically welded studs

are placed in the pans of sheeting ribs deemed to be perpendicular to the steel beam,

no more than two studs are permitted between adjacent sheeting ribs. New rules have

been written to allow shear connectors to be placed closer to steel ribs of closed-rib

profiles.

4 New reference material New reference material has been provided for designers

regarding the design of beams with large web penetrations and design for occupant-

induced vibrations.

5 Reinforcement fyr = 500. The maximum design yield strength has been increased to

500 MPa for the longitudinal shear reinforcement in the composite slab.

The terms ‘normative’ and ‘informative’ are used in this Standard to define the application

of the appendix to which they apply. A ‘normative’ appendix is an integral part of a

Standard, whereas an ‘informative’ appendix is only for information and guidance.

3 AS 2327.1—2003

CONTENTS

Page

SECTION 1 SCOPE AND GENERAL

1.1 SCOPE......................................................................................................................... 6

1.2 GENERAL................................................................................................................... 6

1.3 REFERENCED DOCUMENTS................................................................................... 9

1.4 DEFINITIONS........................................................................................................... 10

1.5 EXISITING STRUCTURES...................................................................................... 16

1.6 DESIGN INFORMATION ........................................................................................ 16

1.7 CONSTRUCTION..................................................................................................... 17

1.8 NOTATION............................................................................................................... 17

SECTION 2 MATERIALS

2.1 STEEL ....................................................................................................................... 25

2.2 CONCRETE AND REINFORCEMENT ................................................................... 25

2.3 MECHANICAL PROPERTIES ................................................................................. 25

SECTION 3 GENERAL DESIGN REQUIREMENTS

3.1 DESIGN .................................................................................................................... 27

3.2 LOADS AND OTHER ACTIONS............................................................................. 28

3.3 DESIGN FOR LIMIT STATES................................................................................. 28

SECTION 4 ACTIONS AND DESIGN SITUATIONS

4.1 GENERAL................................................................................................................. 30

4.2 CONSTRUCTION STAGES ..................................................................................... 30

SECTION 5 EFFECTIVE SECTION AND DESIGN ACTION EFFECTS FOR STRENGTH

DESIGN

5.1 GENERAL................................................................................................................. 32

5.2 EFFECTIVE SECTION OF A COMPOSITE BEAM CROSS-SECTION ................. 32

5.3 CALCULATION OF DESIGN ACTION EFFECTS DUE TO DESIGN LOADS ..... 37

SECTION 6 DESIGN FOR STRENGTH

6.1 GENERAL................................................................................................................. 39

6.2 DESIGN .................................................................................................................... 39

6.3 POTENTIALLY CRITICAL CROSS-SECTIONS .................................................... 41

6.4 CALCULATION OF DESIGN VERTICAL SHEAR CAPACITY (φVu) AND

DESIGN MOMENT CAPACITY (φMbv) AS A FUNCTION OF DEGREE OF

SHEAR CONNECTION (β) ...................................................................................... 42

6.5 CALCULATION OF MINIMUM DEGREE OF SHEAR CONNECTION βi AT

POTENTIALLY CRITICAL CROSS-SECTIONS .................................................... 42

6.6 DISTRIBUTION OF SHEAR CONNECTORS BETWEEN POTENTIALLY

CRITICAL CROSS-SECTIONS AND BEAM ENDS ............................................... 43

SECTION 7 DESIGN FOR SERVICEABILITY

7.1 GENERAL................................................................................................................. 45

7.2 DEFLECTION CONTROL........................................................................................ 45

7.3 CRACK CONTROL .................................................................................................. 47

7.4 VIBRATION CONTROL .......................................................................................... 47

AS 2327.1—2003 4

Page

SECTION 8 DESIGN OF SHEAR CONNECTORS

8.1 GENERAL................................................................................................................. 48

8.2 SHEAR CONNECTORS ........................................................................................... 48

8.3 SHEAR CAPACITY OF SHEAR CONNECTORS ................................................... 50

8.4 DETAILING OF SHEAR CONNECTORS ............................................................... 52

SECTION 9 TRANSFER OF LONGITUDINAL SHEAR IN CONCRETE

9.1 GENERAL................................................................................................................. 60

9.2 DEFINITIONS........................................................................................................... 60

9.3 DESIGN .................................................................................................................... 60

9.4 LONGITUDINAL SHEAR SURFACES ................................................................... 61

9.5 DESIGN LONGITUDINAL SHEAR FORCE (V*L).................................................. 65

9.6 NOMINAL LONGITUDINAL SHEAR CAPACITY (VL)......................................... 66

9.7 TYPES 1, 2 AND 3 LONGITUDINAL SHEAR REINFORCEMENT ...................... 67

9.8 TYPE 4 LONGITUDINAL SHEAR REINFORCEMENT......................................... 67

SECTION 10 DESIGN FOR FIRE RESISTANCE

10.1 REQUIREMENTS..................................................................................................... 70

10.2 DEFINITIONS........................................................................................................... 70

10.3 DETERMINATION OF PERIOD OF STRUCTURAL ADEQUACY....................... 71

10.4 DETERMINATION OF LIMITING TEMPERATURE OF THE STEEL.................. 71

10.5 DETERMINATION OF TIME AT WHICH LIMITING TEMPERATURE IS

ATTAINED FOR PROTECTED MEMBERS ........................................................... 71


ATTAINED FOR UNPROTECTED MEMBERS...................................................... 73

10.7 DETERMINATION OF PSA FROM A SINGLE TEST............................................ 74

10.8 THREE-SIDED FIRE EXPOSURE CONDITION..................................................... 74

10.9 CONNECTIONS AND WEB PENETRATIONS....................................................... 74

10.10 DETERMINATION OF PERIOD OF STRUCTURAL ADEQUACY BY OTHER

CALCULATION METHODS ................................................................................... 75

SECTION 11 CONSTRUCTION

11.1 GENERAL................................................................................................................. 76

11.2 CONSTRUCTION SEQUENCE AND LOADS ........................................................ 76

11.3 STEELWORK ........................................................................................................... 76

11.4 FORMWORK AND FALSEWORK.......................................................................... 76

11.5 REINFORCEMENT .................................................................................................. 77

11.6 CONCRETE .............................................................................................................. 77

11.7 FIRE PROTECTION MATERIAL ............................................................................ 77

SECTION 12 LOAD TESTING

12.1 GENERAL................................................................................................................. 78

12.2 PROOF TESTING ..................................................................................................... 78

12.3 PROTOTYPE TESTING ........................................................................................... 79

12.4 TEST REPORTS ....................................................................................................... 80

5 AS 2327.1—2003

Page

APPENDICES

A LIST OF REFERENCED DOCUMENTS.................................................................. 81

B CALCULATION OF DEFLECTIONS BY SIMPLIFIED METHOD........................ 83

C SUGGESTED LIMITS FOR CALCULATED DEFLECTIONS................................ 90

D CALCULATION OF DESIGN MOMENT CAPACITY (φMbv) AS A

FUNCTION OF DEGREE OF SHEAR CONNECTION (β)............................................ 91

E FLOW CHARTS ..................................................................................................... 107

F CONSTRUCTION STAGES AND MINIMUM CONSTRUCTION LOADS.......... 114

G DESIGN FOR FIRE RESISTANCE OF CONCRETE SLABS................................ 119

H INFORMATION FOR DETERMINATION OF ACTION EFFECTS ..................... 120

I BIBLIOGRAPHICAL REFERENCES .................................................................... 123

AS 2327.1—2003 6

Standards Australia www.standards.com.au

STANDARDS AUSTRALIA

Australian Standard



S E C T I O N 1 S C O P E A N D G E N E R A L

1.1 SCOPE

This Standard sets out minimum requirements for the design, detailing and construction of

simply supported composite beams composed of a steel beam and a concrete slab

interconnected with shear connectors, including applications where the slab incorporates

profiled steel sheeting, as defined in Clause 1.2.

This Standard does not cover the design of composite beams—

(a) where the elements of the steel beam are less than 3 mm thick or the value of the

yield stress (fyb) assumed in design exceeds 450 MPa (see Note 1);

(b) where the strength grade of the slab concrete exceeds 40 MPa;

(c) where the slab is precast or prestressed;

(d) with negative design moments (see Note 2);

(e) subjected to dynamic loads;

(f) for road or railway bridges (see Note 3); or

(g) for fatigue.

NOTE:

1 This does not preclude the use of steels with a minimum yield strength greater than 450 MPa.

2 For the design of composite beams with negative design moments reference may be made to

BS 5950:3:1990, Code of Practice for Design of Simple and Continuous Composite Beams.

3 For the design of composite bridge beams, reference should be made to HB 77 the AUSTROADS

Bridge Design Code.

1.2 GENERAL

1.2.1 Components

This Standard applies only to composite beams for which the components satisfy the

requirements specified in Clauses 1.2.2 to 1.2.5.

1.2.2 Steel beam

The steel beam shall be entirely below, but in contact with, the soffit of the concrete slab,

and shall be of structural steel, symmetrical about its vertical axis (i.e., doubly symmetric

or monosymmetric), suitably proportioned (see Note) and have one of the following forms

(see Figure 1.2.2)—

(a) a hot-rolled I-section, or channel section;

(b) a welded I-section;

(c) a rectangular cold-formed hollow section;


7 AS 2327.1—2003

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(d) a fabricated I-section, Tee section, channel section or rectangular hollow section; or

(e) any of the above sections as appropriate with an additional plate welded to the bottom

flange.

NOTE: Steel beams with a slender section (i.e., λ e > λ ey for any top flange or web plate

element either partially or fully in compression (see Clause 5.2.3.3)) are not permitted.

When a fire resistance level (FRL) must be achieved, a fire protection material may be used

to protect the exposed surfaces of the steel beam.

FIGURE 1.2.2 ALTERNATIVE STEEL BEAM TYPES

1.2.3 Concrete slab

The concrete slab shall be of reinforcement in accordance with AS/NZS 4671, non-

prestressed concrete complying with AS 3600, and be either a solid slab (without a haunch)

or a composite slab (see Figure 1.2.3).


AS 2327.1—2003 8


FIGURE 1.2.3 ALTERNATIVE CONCRETE SLAB TYPES

1.2.4 Profiled steel sheeting

The geometry of the profiled steel sheeting incorporated in a composite slab shall satisfy all

of the following requirements (see Figure 1.2.4(a)):

(a) The overall height of a steel rib (hr) shall be not greater than 80 mm, excluding any

embossments.

(b) The width of the opening at the base of a steel rib (bb) shall be not greater than

20 mm.

(c) The area of the voids formed by the steel ribs in the concrete shall be not greater than

20% of the area of the concrete within the depth of the steel ribs.

(d) The width of the concrete between the mid-height of adjacent steel ribs (bcr) shall be

not less than 150 mm.

(e) The cover slab thickness (that is, the thickness of the concrete above the steel ribs,

which equals Dc − hr) shall be not less than 65 mm.

Longitudinal stiffeners in the pans of the sheeting with an overall height (hs) greater than

10 mm, measured from the same face of the sheet (see Figure 1.2.4(b)), shall be deemed to

be steel ribs for the purpose of this Standard.

Open-rib and closed-rib profiles shall be defined as follows:

(i) Closed-rib profiles All of the steel ribs of a closed-rib profile shall satisfy the

geometric requirements shown in Figure 1.2.4 (c).

(ii) Open-rib profiles A profile that is not a closed-rib profile shall be treated as an

open-rib profile.


9 AS 2327.1—2003


NOTE: Dimensions are to be taken between adjacent sheeting surfaces

(c) Closed-rib profile

FIGURE 1.2.4 PROFILED STEEL SHEETING GEOMETRY

1.2.5 Shear connectors

The shear connectors attached to the top flange of the steel beam shall be any one of the

following three types (see Figure 1.2.5):

(a) Headed studs.

(b) Channels.

(c) High-strength structural bolts.

1.3 REFERENCED DOCUMENTS

The documents referred to in this Standard are listed in Appendix A.


AS 2327.1—2003 10


FIGURE 1.2.5 ACCEPTABLE SHEAR CONNECTOR TYPES

1.4 DEFINITIONS

1.4.1 General

For the purpose of this Standard, the definitions below apply. Definitions applying only to a

particular clause or section are given in that clause or section and referred to below.

1.4.2 Administrative definitions

1.4.2.1 Authority

A body having regulatory powers, in the area in which the structure is to be erected, to

control the design and erection of the structure.

1.4.2.2 Drawings

The drawings forming part of the project documents setting out the work to be executed.

1.4.2.3 May

Indicates the existence of an option.

1.4.2.4 Principal

The purchaser or owner of the structure being constructed or his nominated representative.

1.4.2.5 Shall

Indicates that a statement is mandatory.


11 AS 2327.1—2003


1.4.2.6 Should

Indicates a recommendation.

1.4.2.7 Specification

The specification forming part of the project documents setting out the work to be executed.

1.4.3 Technical definitions

1.4.3.1 Action

The cause of stress, deformation or displacement in a structure, or in a component member

of the structure.

1.4.3.2 Action effect

The force, moment, deformation, or like effect, produced in the members of a structure

(or its foundations) by an action or combination of actions.

1.4.3.3 Capacity factor

A factor by which the nominal capacity or strength is multiplied to obtain the design

capacity or strength.

1.4.3.4 Characteristic strength

The value of a material strength, as assessed by a standard test, which has a 95% probability

of being exceeded in all such tests on the same material.

1.4.3.5 Closed-rib profile

A profiled steel sheeting where the geometry of all of the steel ribs satisfies the geometric

requirements of Figure 1.2.4 (c).

1.4.3.6 Complete shear connection (β = 1)

The condition where the moment capacity of the cross-section of the composite beam is not

governed by the strength of the shear connection.

1.4.3.7 Composite action

Interaction between the steel beam and the concrete slab to resist action effects as a single

structural member; assumed to commence when the concrete in the slab has attained a

compressive strength of at least 15 MPa (i.e., at the start of Construction Stage 5). It is

assumed to be fully developed once the compressive strength of the concrete (estimated by

f′ cj (see Clause 4.2.2)) is equal to or greater than its specified design value f′c (i.e., at or

after the start of Construction Stage 6).

1.4.3.8 Composite beam

A steel beam and a solid or composite slab, interconnected by shear connection to act

together to resist action effects as a single structural member.

1.4.3.9 Composite slab

A cast in situ concrete slab that incorporates profiled steel sheeting as permanent soffit

formwork.

1.4.3.10 Concrete

A mixture of cement, aggregates and water, with or without the addition of chemical

admixtures, which conforms to both AS 1379 and AS 3600.

1.4.3.11 Concrete slab

A slab cast monolithically with in situ concrete and reinforcement, with or without profiled

steel sheeting.


AS 2327.1—2003 12


1.4.3.12 Connector group

(See Clause 9.2).

1.4.3.13 Connector set

(See Clause 9.2).

1.4.3.14 Construction stage

One of the periods defined in Clause 4.2.

1.4.3.15 Cover

The least distance between the surface of reinforcement or shear connectors and the nearest

permanent surface of the concrete, excluding any applied surface finish.

1.4.3.16 Cover slab

Concrete above the steel ribs in a composite slab.

1.4.3.17 Critical cross-section

A transverse cross-section at which the ratio of either the design bending moment (M*) to

the design moment capacity (φMbv), or the design vertical shear force (V*) to the design

vertical shear capacity (φVu) is a maximum.

1.4.3.18 Degree of shear connection (β)

The value obtained when the compressive force in the concrete at the strength limit state

(Fcp) is divided by the compressive force in the concrete corresponding to complete shear

connection in the absence of vertical shear force (Ecc) (see Figure 6.1).

1.4.3.19 Design action effect

The action effect computed from the design action (load).

1.4.3.20 Design capacity

The product of the nominal capacity and the capacity factor.

1.4.3.21 Design life

The period over which a structure or structural element is required to perform its intended

function without undue maintenance.

1.4.3.22 Design load

The combination of loads and load factors as specified in AS/NZS 1170.0.

1.4.3.23 Effective section

The portion of a composite beam cross-section considered effective in resisting action

effects in bending (see Clause 5.2).

1.4.3.24 Effective span

See Clause 5.3.2.

1.4.3.25 Effective width of concrete flange

The overall width of the portion of a concrete slab, at a composite beam cross-section,

considered effective in resisting compression after allowing for shear lag.

1.4.3.26 Effective width of steel flange

The overall width of the portion of a flange of a steel beam, at a composite beam cross-

section, considered effective in resisting compression after allowing for flange buckling.


13 AS 2327.1—2003


1.4.3.27 Exposed surface area to mass ratio

See Clause 10.2.

1.4.3.28 Fire exposure condition

See Clause 10.2.

1.4.3.29 Fire protection system

See Clause 10.2.

1.4.3.30 Fire-resistance level (FRL)

See Clause 10.2.

1.4.3.31 Fire-resistance period

See Clause 10.2.

1.4.3.32 Full interaction

The condition of a composite beam assuming no slip occurs along the length of the beam at

the concrete/steel interface.

1.4.3.33 In-service condition

Period after completion of construction when the structure is serving its intended function.

1.4.3.34 Insulation

See Clause 10.2.

1.4.3.35 Integrity

See Clause 10.2.

1.4.3.36 Lightweight concrete

Concrete, as previously defined, having a saturated surface-dry density in the range

1800 kg/m3 to 2100 kg/m

3.

1.4.3.37 Limit state

Any limiting condition or criterion beyond which a structure, or a member, fails to fulfil its

intended function.

1.4.3.38 Load

An externally applied force.

1.4.3.39 Longitudinal shear plane

See Clause 9.2.

1.4.3.40 Longitudinal shear reinforcement

See Clause 9.2.

1.4.3.41 Longitudinal shear surface

See Clause 9.2.

1.4.3.42 Nominal capacity

The capacity of a member or component calculated, without the capacity factor, in

accordance with this Standard.

1.4.3.43 Nominal load

A load as specified in Clause 4.1.1.


AS 2327.1—2003 14


1.4.3.44 Normal-weight concrete

Concrete, as previously defined, having a saturated surface-dry density greater than

2100 kg/m3 and less than or equal to 2800 kg/m

3.

1.4.3.45 One-way action

Flexural action significant in one direction only.

1.4.3.46 One-way slab

A solid or composite slab characterized by one-way action.

1.4.3.47 Open-rib profile

A profiled steel sheeting with open and possibly closed steel ribs.

1.4.3.48 Partial shear connection (β < 1.0)

The condition for which the moment capacity of the cross-section of the composite beam is

governed by the strength of the shear connection.

1.4.3.49 Period of structural adequacy (PSA) (fire)

See Clause 10.2.

1.4.3.50 Ponding

Appreciably non-uniform depth of slab as a result of the steel beam or formwork deflecting

under the weight of the plastic concrete and slab reinforcement.

1.4.3.51 Potentially critical cross-section

A transverse cross-section that is likely to be critical (see Clause 6.3).

1.4.3.52 Precast slab

Slab incorporating precast concrete units with or without cast in situ concrete.

1.4.3.53 Prestressed slab

Slab incorporating prestressed tendons.

1.4.3.54 Profiled steel sheeting

Steel sheeting cold-formed into a profile used as permanent formwork for the soffit of

composite slabs.

1.4.3.55 Proof testing

The application of specified test loads to a member or assemblage of members, to

demonstrate adequate structural performance of only that member or assemblage.

1.4.3.56 Prop

A temporary support fitted beneath a steel beam or formwork to support loads during

construction.

1.4.3.57 Prototype (fire)

See Clause 10.2.

1.4.3.58 Prototype testing

The application of limit-state test actions to two or more prototype members or

assemblages, which are representative of a group of members or assemblages nominally

identical with those tested, for the purpose of demonstrating conformance of the group with

specified limit-state criteria.


15 AS 2327.1—2003


1.4.3.59 Reinforcement, reinforcing steel

Steel bar, wire, or fabric (but not tendons or fibres) placed in a concrete slab.

1.4.3.60 Serviceability limit state

The loss of fitness for intended use under specified in-service conditions.

1.4.3.61 Shear connection

The interconnection between the steel beam and concrete slab of a composite beam, which

enables the two components to act together as a single structural member, comprising the

shear connectors, slab concrete and longitudinal shear reinforcement.

1.4.3.62 Shear connector

A mechanical device attached to the top flange of a steel beam which forms part of the

shear connection.

1.4.3.63 Shear ratio (γ)

The ratio at a cross-section of the design vertical shear force (V*) to the design vertical

shear capacity (φVu).

1.4.3.64 Simply supported beam

A beam assumed to act as a single-span member without negative design moments.

1.4.3.65 Solid slab

A concrete slab with a flat soffit and without a haunch, cast in situ on removable formwork

and reinforced in accordance with AS 3600.

1.4.3.66 Standard fire test

See Clause 10.2.

1.4.3.67 Stickability (fire)

See Clause 10.2.

1.4.3.68 Strength limit state

Collapse, or loss of structural integrity, under specified extreme-load conditions.

1.4.3.69 Structural adequacy (fire)

See Clause 10.2.

1.4.3.70 Tensile strength

The maximum strength in tension specified for the relevant grade and type of steel in the

appropriate Australian Standard.

1.4.3.71 Tributary area

See Clause 5.3.2.

1.4.3.72 Two-way action

Flexural action significant in two directions, usually at right angles to one another.

1.4.3.73 Two-way slab

A solid slab characterized by two-way action.

1.4.3.74 Yield strength (or stress)

The minimum yield stress in tension specified for the grade and type of steel in the

appropriate Australian Standard.


AS 2327.1—2003 16


1.5 EXISITING STRUCTURES

When the strength or serviceability of an existing structure is to be evaluated, the general

principles of this Standard may be applied using the actual properties of the materials in the

structure. The evaluation may include the proof testing of beams in accordance with

Clause 12.2.

1.6 DESIGN INFORMATION

1.6.1 Design data

The following design details shall be shown on the drawings:

(a) The reference number and date of issue of applicable and current design Standards

and, if applicable, any amendments to them.

(b) The nominal design live loads during construction and in-service, as appropriate.

(c) The durability exposure classification for the concrete and, if applicable, the

corrosion protection for the exposed steelwork and profiled steel sheeting.

(d) The required fire-resistance level, if applicable.

(e) The grades and types of reinforcement.

(f) The grades of steel in the steel beams.

(g) The types and, if applicable, grades of shear connectors and their method of

attachment.

(h) The type, class and strength designation of the concrete.

1.6.2 Design details

The project drawings or the specification, or both, shall include the following design details

as appropriate:

(a) The dimensions and, if applicable, camber and designation of each steel member.

(b) The support or connection details for the steel beams including location, size, grade

and category of bolts or welds, as applicable.

(c) Details of the type, size, location and spacing of shear connectors, particularly in

relation to the position of profiled steel sheeting ribs.

(d) The overall thickness of the slab inclusive of profiled steel sheeting, if applicable,

and the size and location of any openings, rebates, major voids or conduits in the slab.

(e) The grade, size, quantity and location of all reinforcement, and other structural

embedments, as appropriate.

(f) The finish and method of control for unformed concrete surfaces.

(g) In the case of solid slabs, the class of formwork for the surface finish specified in

accordance with AS 3610.

(h) In the case of composite slabs, the proprietary name, base metal thickness, coating

class and similar relevant data for the profiled steel sheeting, or appropriate selection

or performance criteria.

(i) The concrete curing procedure.

(j) The location and details of any movement joints or planned construction joints in the

concrete slabs.

(k) The minimum period of time before stripping of forms or removal of props, as

appropriate.


17 AS 2327.1—2003


(l) The values of the nominal live loads used in design.

(m) The assumed construction sequence.

(n) The climatic or other local conditions relevant to the durability design of the

structure.

(o) The design life of the structure (if applicable).

(p) Any other constraint on construction assumed in the design.

(q) Fire-resistance requirements and fire-protection details, if applicable.

(r) Any other requirements.

1.7 CONSTRUCTION

Composite beams designed in accordance with this Standard shall be constructed so that all

the requirements of the design, as contained in the project drawings and specification, are

satisfied.

1.8 NOTATION

The symbols used in this Standard are listed below. Symbols that occur in more than one

clause are defined below and used in the various clauses without further reference. Symbols

which occur only in one clause are defined in that clause as well as being listed below.

Unless otherwise specified, the following rules apply:

(a) Where non-dimensional ratios are involved, both the numerator and denominator are

expressed in identical units.

(b) The dimensional units for length, force and stress in all expressions or equations are

to be taken as millimetres (mm), newtons (N) and megapascals (MPa) respectively.

(c) The units of fractional powers of stress (e.g.cf ′ ) are to be taken as those for stress.

(d) An asterisk superscript placed after a symbol (e.g. M*) denotes a design action effect

resulting from the design load for the strength limit state.

A = tributary area associated with a steel or composite beam for the

calculation of nominal live load

Af = cross-sectional area of a flange of the steel beam

Af1, Af2 = values of Af for top and bottom flanges, respectively

As = cross-sectional area of the steel beam

Asc = cross-sectional area of the shank of a headed stud, or the minor

diameter area of a high-strength structural bolt as defined in

AS 1275

Asp.b = cross-sectional area of bottom-face reinforcement crossing a

longitudinal shear plane through the concrete flange (see

Figure 9.4.1(a))

Asp.t = cross-sectional area of top-face reinforcement crossing a

longitudinal shear plane through the concrete flange (see

Figure 9.4.1(a))

Asv = cross-sectional area of reinforcement crossing a longitudinal shear

surface through the concrete flange

Asv.min = the minimum cross-sectional area required of reinforcement

crossing a longitudinal shear surface through the concrete flange


AS 2327.1—2003 18


Asv.1, Asv.2, Asv.3 = values of Asv corresponding to shear surface types 1, 2 and 3,

respectively

Aw = cross-sectional area of the web(s) of the steel beam

b = clear width of plate element outstand

b1, b2 = centre-to-centre spacing of adjacent beams or distance from centre

of steel beam to edge of slab outstand (see Figure 5.2.2.1)

bb = width of opening at base of steel rib in a composite slab (see

Figure 1.2.4(a))

bcf = effective width of the concrete slab compression flange (see

Figure 5.2.2.1)

bcr = width of the concrete rib in a composite slab at mid-height of the

steel ribs

= sr – bsr

be1, be2 = concrete slab effective width outstands on opposite sides of steel

beam centre-line (see Figures 5.2.2.1 and 9.5)

bf = width of a steel beam flange

bs = support width

bsf1 = effective width of steel beam top flange

bsf2 = overall width of steel beam bottom flange

bsr = width of steel rib in a composite slab at its mid-height (see

Figure 1.2.4(a))

bx = overall width of shear connectors at a beam cross-section (see

Figure 9.4.1)

by1, by2 = segment lengths of shear surface perimeter (see Figure 9.4.2.5)

c1, c2 = constants (see Paragraph B3.2, Appendix B)

Db = overall depth of a composite beam

Dc = overall depth of a concrete slab including the thickness of any

profiled steel sheeting if present

Ds = overall depth of a steel beam

d1 = clear depth between flanges of a steel beam ignoring fillets or welds

db = nominal diameter of a reinforcing bar (see Clause 9.7.3)

dbs = nominal shank diameter of a headed-stud or a high-strength

structural bolt shear connector

dc = depth of the assumed uniform compressive stress block in the

concrete slab at the strength limit state

dh = calculated depth of the compressive zone below the top of the

concrete slab at the strength limit state

dsg = distance from the top of the concrete slab to the centroid of the steel

beam

dsr = distance from the top of the concrete slab to the line of action of

either Fst or Fstf

Ec = elastic modulus of the slab concrete


19 AS 2327.1—2003


EcT = elastic modulus of the slab concrete at T°C > 20°C

Es = elastic modulus of steel at 20°C (= 2 × 105 MPa)

EsT = elastic modulus of steel at T°C > 20°C

Fb = balancing compressive force in steel beam [either (Fsc − 2Fscf) or

(Fsc − 2Fscf − 2Fscw)]

Fc = compressive force in the concrete slab at a cross-section at the

strength limit state

= Fcc or Fcp as appropriate

Fc1 = longitudinal compressive capacity of concrete cover slab within slab

effective width

Fc2 = longitudinal compressive capacity of concrete between steel

sheeting ribs within slab effective width

Fcc = compressive force in concrete slab at a cross-section with complete

shear connection where γ ≤ 0.5 at the strength limit state

Fcc.i = value of Fcc corresponding to potentially critical cross-section (i)

Fccf = compressive force in concrete slab at a cross-section with complete

shear connection where γ = 1.0 at the strength limit state

Fcp = compressive force in concrete slab at a cross-section with partial

shear connection where γ ≤ 0.5 at the strength limit state

Fcp.i = value of Fcp corresponding to potentially critical cross-section (i)

Fcpf = compressive force in concrete slab at a cross-section with partial

shear connection where γ = 1.0 at the strength limit state

Fs = resultant tensile force in steel beam at the strength limit state

Fsc = balancing compressive force in steel beam [either (Fst − 2Fcp) or

(Fstf − Fccf)]

Fscf = compressive capacity of steel beam top flange, assuming entire

effective flange area is at yield stress fyf

Fscw = compressive capacity of steel beam web(s), assuming entire

effective portion is at yield stress fyw

Fst = tensile capacity of steel beam, assuming that the entire cross-

sectional area has yielded in tension

Fstf = tensile capacity of the steel beam ignoring web(s), assuming that the

entire cross-sectional area of the flanges has yielded in tension

f′ c = 28 day characteristic compressive cylinder strength of concrete

f′ cj = estimated characteristic compressive strength of concrete at j days

(see Clause 4.2.2) but taken as not greater than f′c

fcmj = average compressive strength of sample cylinders after j days of site

curing (see Clause 4.2.2)

fds = design shear capacity of a shear connector (see Clause 8.3.4)

fmax = maximum stress in steel beam (see Paragraph B4)

fuc = tensile strength of the shear-connector material used in design

fvs = nominal shear capacity of a shear connector (see Clause 8.3.2)


AS 2327.1—2003 20


fy = yield strength of steel used in design

fyb = yield strength of steel beam used in design

fyf, fyw = yield strength of the flange and web, respectively, of the steel beam

fyr = yield strength of the steel reinforcement used in design

fyT = yield strength of steel beam at T°C

G = total dead load

Gsup = superimposed dead load

GC1.3 = permanent dead load which arises during Construction Stages 1 to 3

hc = overall height of a shear connector (see Clause 9.4.2.4)

he = effective thickness of concrete slab

hi = thickness of fire protection material

hr = height of the steel ribs in profiled steel sheeting

hs = height of longitudinal stiffener in profiled steel sheeting (see

Figure 1.2.4(b))

Iet = effective second moment of area of a composite cross-section

Ieti = value of Iet under immediate loads

letI = value of Iet under long-term loads

Is = second moment of area of the steel beam about its centroid of area

It = second moment of area of transformed section with respect to steel

Iti = transformed second moment of area of a composite beam

cross-section under immediate loads, taken about the centroid of the

transformed area

ltI = transformed second moment of area of a composite beam

cross-section under long-term loads, taken about the centroid of the

transformed area

k = elastic neutral axis parameter

k0 to k6 = regression coefficients (see Section 10)

kn = a load-sharing factor (see Clause 8.3.4)

ksm = exposed surface area to mass ratio

ksm1 = exposed surface area to mass ratio above a penetration

ksm2 = exposed surface area to mass ratio below a penetration

L = distance between the centre-lines of adjacent members supporting a

composite beam; or

= distance available for reinforcement anchorage (see Clause 9.7.3)

Lef = effective span of a composite beam (see Clause 5.3.3); or

= effective span of profiled steel sheeting (see Paragraph C2,

Appendix C)

Ln = clear distance between the flanges of adjacent steel beams spanning

in the same direction


21 AS 2327.1—2003


Lsy.t = development length for reinforcement in tension (see Clause 9.7.3)

Lw = greatest internal dimension of holes drilled or cut in steel beam web

l = length of channel shear connector (see Figure 8.2)

M* = design bending moment at a cross-section

Mb = nominal moment capacity of a composite cross-section where

γ ≤ 0.5 and 0 < β < 1.0

Mb.5 = value of Mb corresponding to β = 0.5

Mb.ψ = value of Mb corresponding to β = ψ

Mbc = nominal moment capacity of a composite beam cross-section where

γ ≤ 0.5 and β = 1.0

Mbf = nominal moment capacity of a composite beam cross-section where

γ = 1.0 and 0 < β < ψ, neglecting any contribution of the steel beam

web(s)

Mbfc = nominal moment capacity of a composite beam cross-section where

γ = 1.0 and β = 1.0, neglecting any contribution of the steel beam

web(s)

Mbv = nominal moment capacity of a composite beam cross-section where

0 ≤ γ ≤ 1.0 and 0 ≤ β ≤ 1.0

Mbv.0 = value of Mbv corresponding to β = 0

Mbv.ψ = value of Mbv corresponding to β = ψ

Mbvc = nominal moment capacity of a composite beam cross-section where

0 ≤ γ ≤ 1.0 and β = 1.0

Ms = nominal moment capacity of steel beam section

Msf = nominal moment capacity of steel beam section neglecting any

contribution of the web(s)

n = total number of shear connectors provided between a cross-section

and an end of the composite beam

nA = number of shear connectors between a potentially critical cross-

section (i) and end A of a beam (see Figure 6.1)

nB = number of shear connectors between a potentially critical cross-

section (i) and end B of a beam (see Figure 6.1)

ni = minimum number of shear connectors (with the same design shear

capacity fds) between a potentially critical cross-section i and the

ends of the beam to satisfy the design requirement φMbv ≥ M*

n′ i = number of shear connectors provided which are considered fully

effective in contributing to the design moment capacity (φMbv) of a

potentially critical cross-section (i)

nic = minimum number of shear connectors (with the same design shear

capacity fds) required between a potentially critical cross-section (i)

and the ends of the beam to achieve complete shear connection

ni.min = the lesser number of shear connectors provided between a

composite beam cross-section and the ends of the beam

nx = number of shear connectors in a group at a transverse cross-section

of a composite beam


AS 2327.1—2003 22


Q = live load

Ru = nominal capacity of a composite member, or a component of the

member, to resist action effects at the strength limit state

Rs = nominal capacity of a composite member, or a component of the

member, to resist action effects at the serviceability limit state

re = elastic neutral axis parameter measured from below the steel beam

top flange (see Table 5.1)

rf = maximum value along the length of the beam of the ratio of the

design bending moment (M*) under design load for fire to the

design moment capacity (φMbv) at room temperature

rp = plastic neutral axis parameter (see Table 5.1)

rl = the corner outside radius of a rectangular hollow section (see

Figure 8.4.3.1)

S* = design action effects in general

s = standard deviation

sc = longitudinal spacing of shear connectors between adjacent groups

sr = transverse spacing of steel ribs in a profiled steel sheet (see

Figure 1.2.4(a))

T = steel temperature in degrees Celsius

Tl = limiting steel temperature in degrees Celsius

t = plate element thickness; or

= time

tf = thickness of the flange of a steel beam

tf1, tf2 = values of tf corresponding to the top and bottom flanges,

respectively

tw = thickness of the web(s) of a steel beam

t′w = effective thickness of non-compact web(s) of a steel beam (see

Figure 5.2.3.3(b))

u = perimeter length of a shear surface

u1, u2, u3 = values of u corresponding to Type 1, 2 and 3 shear surfaces (see

Figure 9.4.2.5)

V* = design vertical shear force acting at a composite beam cross-section

V*L = design longitudinal shear force per unit length acting on a

longitudinal cross-section of a concrete slab flange

V*L.tot = total design longitudinal shear force per unit length of beam

VL = nominal longitudinal shear capacity per unit length of the concrete

slab at the strength limit state

Vu = nominal vertical shear capacity of a composite beam cross-section

at the strength limit state


23 AS 2327.1—2003


x = distance from outside edge of effective width to centre of

longitudinal shear surface (see Clause 9.5); or

= depth of non-compact portion of web to be ignored in design (see

Figure 5.2.3.3(a))

Zcb = section modulus of the composite beam corresponding to the

extreme bottom fibres of the steel beam

Zct = section modulus of the composite beam corresponding to the

extreme top fibres of the steel beam

Zsb = section modulus of the steel beam corresponding to the extreme

bottom fibres of the steel beam

Zst = section modulus of the steel beam corresponding to the extreme top

fibres of the steel beam

α = modular ratio Es/Ec or EsT/EcT

β = degree of shear connection at a cross-section

= Fcp/Fcc (see Figure 6.1)

iβ = minimum degree of shear connection at a potentially critical cross-

section i to satisfy the design requirement φMbv ≥ M*

βm = degree of shear connection at the maximum moment cross-section

of a composite beam

γ = shear ratio at a composite beam cross-section

= V*/(φVu ) ≤ 1.0

∆ = maximum deflection of a composite beam under serviceability loads

δC1.3 = immediate deflection of steel beam during Construction

Stages 1 to 3

δC5.6 = immediate deflection of composite beam during Construction

Stages 5 to 6

δIi = immediate deflection of composite beam during in-service condition

δIl

= long-term creep deflection of composite beam during in-service

condition

δIsh = long-term shrinkage deflection of composite beam during in-service

condition

incδ = incremental deflection (see Paragraph B1)

δtot = total deflection (see Paragraph B1)

ε = yield stress factor (see Figure 5.2.3.3(a))

θ = acute angle between the steel ribs of a composite slab and the

longitudinal axis of the steel beam

λ = factor accounting for the inclination of profiled steel sheeting ribs

with respect to longitudinal axis of steel beam (see

Figure 5.2.2.2(b))

λe = plate element slenderness (see Clause 5.2.3.3)

λep = plate element plasticity slenderness limit

λey = plate element yield slenderness limit


AS 2327.1—2003 24


ρc = density of concrete

φ = capacity factor relevant to a strength limit state (see Clause 3.3.1)

ψ = value of β corresponding to complete shear connection of a

composite beam ignoring the presence of the steel beam web(s)

= Fccf/Fcc (see Paragraph D3.3, Appendix D)

ψl = long-term live load factor used in assessing the design load for the

serviceability limit state

ψs = short-term live load factor used in assessing the design load for the

serviceability limit state


25 AS 2327.1—2003


S E C T I O N 2 M A T E R I A L S

2.1 STEEL

2.1.1 Structural steel

Structural steel used in the steel beam component of the composite beam shall comply with

AS 1163, AS/NZS 1594, AS 3678, AS 3679.1 or AS 3679.2, as appropriate. Cold-formed

rectangular hollow steel sections manufactured in accordance with AS 1163 shall be grades

C350, C350L0, C450 or C450L0.

2.1.2 Bolts, nuts and washers

Bolts, nuts and washers used for fabricating and erecting the steel beam shall comply with

AS 1110, AS 1111, AS 1112 or AS/NZS 1252, as appropriate.

2.1.3 Welds and welding

Welding consumables, deposited weld metal and welding used to fabricate the steel beam or

attach channel shear connectors to the top flange shall comply with AS 1554.1, and welding

of headed-stud shear connectors shall comply with AS 1554.2.

2.1.4 Shear connectors

Shear connectors shall comply with AS 1554.2, AS/NZS 1252 or AS 3679.1, as appropriate.

Alternatively, shear connectors not complying with the above may be used, provided that—

(a) their mechanical and other physical properties are not inferior; and

(b) they comply with the other relevant requirements of this Standard.

2.1.5 Profiled steel sheeting

The steel strip used to produce the profiled steel sheeting shall comply with AS/NZS 1365

and AS 1397. As an additional requirement, the amount of oil residue on the surface of

profiled steel sheeting after manufacture shall not exceed 200 mg/m2.

2.2 CONCRETE AND REINFORCEMENT

2.2.1 Concrete

The ingredients for, and the manufacture of, fresh (plastic) concrete used for the in situ

concrete slab of a composite beam, shall comply with AS 1379. The resulting hardened

concrete shall comply with AS 3600.

2.2.2 Reinforcement

Reinforcement used in the concrete slab of a composite beam shall comply with

AS/NZS 4671.

2.3 MECHANICAL PROPERTIES

The mechanical properties used for calculating the nominal (unfactored) strengths of the

component parts of the composite beam shall be determined in accordance with the

following:

(a) Steel sections AS 4100, Section 2.

(b) Bolts and nuts AS 1111 and AS 1112.

(c) Welds AS 1554.1 and AS 1554.4.


AS 2327.1—2003 26


(d) Shear connectors of the following types (see also Clause 8.2.1):

(i) Channels AS/NZS 3679.1.

(ii) Headed studs AS 1554.2.

(iii) High-strength structural bolts (Grade 8.8) AS/NZS 1252.

(e) Concrete and reinforcement AS 3600 and AS/NZS 4671.

(f) Galvanized steel strip for profiled steel sheeting AS 1397.


27 AS 2327.1—2003


S E C T I O N 3 G E N E R A L D E S I G N

R E Q U I R E M E N T S

3.1 DESIGN

3.1.1 Aim

The aim of structural design in accordance with this Standard is to provide a composite

beam that has adequate strength, is serviceable, stable, durable and fire-resistant (if

required), and satisfies other objectives such as economy and ease of construction.

A structural member has adequate strength and is serviceable if the probabilities of

structural failure and of loss of serviceability throughout its intended life are acceptably

low.

A structural member is stable overall if it does not overturn, tilt or slide throughout its

intended life.

A structural member is durable if it withstands the expected wear and deterioration

throughout its intended life without the need for undue maintenance or repair.

3.1.2 Requirements

The design of a composite beam and its components shall take into account, as appropriate,

the limit states of stability, strength, serviceability, fire resistance and any other relevant

design criteria, in accordance with the procedures specified in this Section.

Prior to the commencement of composite action, the design of the composite beam

components shall be in accordance with Clause 3.1.3.

NOTES:

1 A flowchart showing the sequence of the overall design process with respect to the various

limit states and construction stages is given in Appendix E.

2 Relevant construction stages are described in Appendix F.

3.1.3 Design of composite beam components

3.1.3.1 Steel beam

Prior to the development of composite action (i.e., Construction Stages 1 to 4), the steel

beam shall be designed in accordance with AS 4100 for the loads and other actions

specified in Clause 3.2. During construction and the in-service condition, end supports and

connections of the steel beam shall satisfy the relevant requirements of AS 4100.

NOTE: Where the formwork consists of profiled steel sheeting, the degree of lateral restraint

provided to the steel beam by the sheeting will depend on, amongst other things, the flexural

stiffness of the sheeting, the orientation of the sheeting ribs and the strength of the connection

between the sheeting and the beam.

3.1.3.2 Concrete slab

The concrete slab may be either a solid slab, or a composite slab (see Clause 1.2.3). The

slab shall be designed in accordance with AS 3600 if it is either a solid slab, or a composite

slab but no composite action between the concrete and the profiled steel sheeting is

considered. When composite action between the concrete and the profiled steel sheeting is

taken into account in design, appropriate design information shall be used.

NOTE: Design provisions for composite slabs are currently being prepared. In the interim, the

proprietary literature of profiled steel sheeting manufactures may be used, provided it is

supported by adequate test data.


AS 2327.1—2003 28


3.1.3.3 Profiled steel sheeting

Prior to the development of composite action (i.e., Construction Stages 1 to 4), the profiled

steel sheeting in a composite slab shall be designed in accordance with an appropriate

method for the loads and other actions defined in Clause 3.2. The calculated deflections

under these conditions shall not exceed the limits specified in Clause 7.2.

NOTE: In the absence of an appropriate Australian Standard, methods given in the proprietary

literature of the profiled steel sheeting manufacturer may be used, provided that they are

supported by adequate test data.

3.1.4 Composite beam minimum slab outstand

The outstand of a concrete slab (either solid or composite), which forms the flange of a

composite edge beam, shall be at least 150 mm wide measured from the vertical outside

edge of the slab to the edge of the nearest shear connector (see Figure 3.1.4).

FIGURE 3.1.4 COMPOSITE BEAM MINIMUM SLAB OUTSTAND

3.2 LOADS AND OTHER ACTIONS

3.2.1 Loads

The design of a composite beam for strength, serviceability, stability and fire resistance

shall take account of the action effects arising directly from the nominal loads specified in

Clause 4.1.1.

3.2.2 Other actions

Any other actions which significantly affect the strength, serviceability, stability or fire

resistance of the composite beam including but not limited to those actions specified in

Clause 4.1.2, shall be taken into account when determining the design loads.

3.2.3 Design loads

The design loads for the limit states of strength, serviceability, stability and fire resistance

shall be determined from Clause 4.1.4.

3.3 DESIGN FOR LIMIT STATES

3.3.1 Design for strength

Once composite action is fully developed (i.e., after Construction Stage 5 when f′cj ≥ f′ c),

the composite beam shall be proportioned and the shear connection between the steel beam

and the concrete slab detailed, so that, under the design actions for the strength limit state

(S*), the design capacity (φRu) at every cross-section satisfies the following inequality:


29 AS 2327.1—2003


*u

SR ≥φ

where

φ = an appropriate capacity factor not greater than the value given in

Table 3.1

Ru = the relevant nominal capacity determined in accordance with Sections 6,

8 and 9

S* = the corresponding design action effect determined in accordance with

Section 5 for the appropriate design loads

TABLE 3.1

CAPACITY FACTOR FOR THE STRENGTH LIMIT STATE

Type of action effect Capacity factor (φφφφ)

Bending

(a) Propped construction: Construction Stage 5

(see Clause 4.2.3)

0.70

(b) All other cases 0.90

Vertical shear 0.90

Longitudinal shear

(a) Concrete slab 0.70

(b) Shear connectors 0.85

3.3.2 Design for serviceability

The composite beam shall be designed so that, under the design actions for the

serviceability limit state, its deflection and vibration, as well as cracking of the concrete

slab, shall each be controlled in accordance with Section 7.

3.3.3 Design for durability

The durability requirements of AS 3600 and AS 4100 shall be satisfied for the concrete slab

and the steel beam respectively. For composite slabs, the manufacturer’s recommendations

regarding the durability of profiled steel sheeting shall be followed. Concrete cover to shear

connectors shall satisfy the requirements of Clause 8.4.4.

3.3.4 Design for fire resistance

Where appropriate, the composite beam shall be designed and detailed in accordance with

Section 10 so that its fire-resistance period for structural adequacy is not less than the

corresponding period specified for the required fire-resistance level. The concrete slab

component of the composite beam shall be designed and detailed in accordance with

Appendix G, so that its fire-resistance periods for structural adequacy, insulation and

integrity are not less than the corresponding periods specified by the required fire-resistance

level.

3.3.5 Design by prototype testing

Notwithstanding the requirements of Clauses 3.3.1 and 3.3.2, a composite beam may be

designed for strength or deflection, or both, by load testing two or more prototypes in

accordance with Clause 12.3, using appropriate design loads determined from Clause 4.1.4.

If this alternative procedure is adopted, the beam shall also be designed for vibration,

durability and fire resistance, as necessary, in accordance with the requirements of

Clauses 3.3.2, 3.3.3 and 3.3.4 respectively.


AS 2327.1—2003 30


S E C T I O N 4 A C T I O N S A N D D E S I G N

S I T U A T I O N S

4.1 GENERAL

4.1.1 Actions

The design of the member for the limit states specified in Clause 3.3 shall take account of

the action effects directly arising from the following actions:

(a) Permanent and imposed, wind, snow and earthquake loads determined in accordance

with AS/NZS 1170.1, AS/NZS 1170.2, AS/NZS 1170.3 and AS 1170.4, respectively.

(b) Construction loads, determined in accordance with Appendix F.

(c) Other specific loads, as required.

Uniformly distributed imposed loads for the in-service condition may be reduced in

accordance with Clause 4.1.3.

4.1.2 Other actions

Any other action that may significantly affect the stability, strength, or serviceability of the

member, including but not limited to the following, shall be taken into account:

(a) Removal of construction props.

(b) Foundation movement.

(c) Temperature changes and gradients.

(d) Transient dynamic actions.

(e) Shrinkage or creep of concrete.

4.1.3 Reduction of uniformly distributed imposed loads

Uniformly distributed imposed loads acting on the composite beam during the in-service

condition may be reduced, when appropriate, in accordance with AS/NZS 1170.1, taking

into account the magnitude of the tributary area (see Clause 5.3.5).

NOTE: Tributary area (A) should be calculated in accordance with Clause 5.3.5 considering

whether the concrete slab exhibits either one-way or two-way action.

4.1.4 Design loads

Except as noted herein, the design loads for the relevant limit state shall be determined

from the appropriate combinations of actions specified in AS/NZS 1170.0 and AS 1170.4

and, if applicable, shall include any other actions, appropriately factored.

4.2 CONSTRUCTION STAGES

4.2.1 General

For the purpose of determining the design actions, action effects and member capacities,

due account shall be taken of the construction stages given in Clauses 4.2.2 and 4.2.3,

which are affected by the development of composite action (see also Appendix F).


31 AS 2327.1—2003


4.2.2 Prior to development of composite action

Until such time as the concrete in the slab has attained a compressive strength of 15 MPa,

no composite action between the steel beam and the concrete shall be assumed. This

encompasses Construction Stages 1 to 4, which are distinguished as follows:

(a) Stage 1 Period between when the steelwork is erected, and the formwork is placed

and, if appropriate, fixed to the steel beams.

(b) Stage 2 Period between the end of Construction Stage 1 and immediately prior to the

commencement of casting the slab concrete.

(c) Stage 3 Period between commencement of casting the slab concrete and its initial set

under the prevailing site conditions.

(d) Stage 4 Period from the initial set of the slab concrete until its compressive strength

(estimated by f′ cj) reaches 15 MPa.

NOTES:

1 An estimate of the characteristic compressive strength of the slab concrete, at an age of ‘j’

days (f′ cj) may be obtained from compression tests on cylinder specimens of the concrete that have been subjected to the same curing conditions as the slab for that period, using

the following equation:

ccmjcj 65.1 fsff ′≤−=′

where

f′ cj = the estimated characteristic compressive strength of concrete at j days

fcmj = the average compressive strength of sample cylinders after j days of site

curing

s = the standard deviation of sample strengths of the grade of concrete used

2 The 7 day mean strength of normal class concrete can be estimated using AS 1379. For

example, if the concrete has been continuously moist cured, an average compressive

strength of not less than 15 MPa may be expected in 7 days by Grades N32 and stronger

grades; however, if 15 MPa is required at a time less than 7 days, special class concrete

may need to be specified.

4.2.3 After development of composite action

Once the concrete in the slab has attained a compressive strength of 15 MPa, development

of composite action between the steel beam and the concrete may be assumed. This

encompasses Construction Stages 5 and 6, which are distinguished as follows:

(a) Stage 5 Period from the end of Construction Stage 4 until the characteristic strength

of the slab concrete reaches its specified design value (f′c) (see Note 1).

(b) Stage 6 Period following the end of Construction Stage 5 to the end of construction

immediately prior to the in-service condition (see Note 2).

NOTES:

1 Props to either the concrete slab or steel beam may be removed during Construction Stage 5,

provided the strength of the composite beam is checked in accordance with Clause 3.3.1.

2 By the end of Construction Stage 6 any props present should have been removed.

3 The construction stages defined in Clauses 4.2.2 and 4.2.3 assume that the principal

construction activities and processes are as shown in Figure F1, Appendix F.


AS 2327.1—2003 32


S E C T I O N 5 E F F E C T I V E S E C T I O N A N D

D E S I G N A C T I O N E F F E C T S F O R S T R E N G T H

D E S I G N

5.1 GENERAL

The effective section of a composite beam cross-section shall be determined in accordance

with Clause 5.2 and used for strength design in accordance with Section 6. The effective

section shall be determined for each potentially critical cross-section defined in Clause 6.3,

except at the ends of the beam where the steel beam alone shall be assumed to act.

The design action effects arising from the design loads specified in Clause 4.1.4 for the

strength limit state after the development of composite action, (i.e., Construction Stages 5

and 6 as defined in Clause 4.2.3 and for the in-service condition) shall be determined in

accordance with the procedure given in Clause 5.3.

NOTE: The design action effects relevant here are the design vertical shear force V* and the

design bending moment M*.

5.2 EFFECTIVE SECTION OF A COMPOSITE BEAM CROSS-SECTION

5.2.1 General

Allowance shall be made for the in-plane shear flexibility (shear-lag) of a concrete

compression flange, by using an effective width of flange calculated in accordance with

Clause 5.2.2.

The region of the concrete slab within the effective width shall be designed for longitudinal

shear in accordance with Section 9.

The portion of the steel beam considered to form part of the effective section of the

composite beam cross-section shall be determined in accordance with Clause 5.2.3.

Any vertical construction joint that falls within the effective width shall be designed in

accordance with Section 9, taking into account the surface condition of the original concrete

face. Any concrete that falls above a horizontal construction joint (e.g., when a screed is

poured on top of an existing slab) shall be ignored when calculating the effective section,

unless the joint is designed for longitudinal shear and the specified compressive strength f′c of the concrete is at least as great as that assumed in design for the remainder of the slab.

NOTE: The procedure that should be followed is shown in Figure E2 of Appendix E.

5.2.2 Effective width of concrete compression flange

5.2.2.1 Solid slab

Where the concrete flange is a solid slab, its effective width (bcf) shall be calculated as the

sum of the distances be measured on each side of the centre-line of the steel beam (see

Figure 5.2.2.1), where be is in each case the smallest of—

(a) Lef/8, where Lef is the effective span of the beam calculated in accordance with

Clause 5.3.3;

(b) in the case of a concrete slab with a free edge (i.e., an edge beam situation), either the

perpendicular distance to the edge measured from the centre-line of the beam, or

6 times the overall depth Dc of the concrete slab plus half the width of the steel beam

flange bsf1; and


33 AS 2327.1—2003


(c) in the case of a concrete slab that spans between two steel beams (i.e., either an edge

beam or internal beam situation), either half the centre-to-centre distance between the

steel beams or 8 times the overall depth Dc of the concrete slab plus half the width of

the steel beam flange bsf1.

When a slab has pockets or cut-outs within its effective width then, at the cross-sections of

concern, bcf shall be reduced by the width they encroach into this region.

FIGURE 5.2.2.1 EFFECTIVE WIDTH OF CONCRETE COMPRESSION FLANGE AT A

COMPOSITE BEAM CROSS-SECTION — SOLID SLAB CASE

5.2.2.2 Composite slab

Where the concrete flange is a composite slab, the effective width of the flange (bcf)—

(a) for the portion of the slab above the ribs, shall be determined in accordance with

Clause 5.2.2.1; and


AS 2327.1—2003 34


(b) for the portion of the slab within the depth of the ribs, shall be taken as the value

obtained from (a) multiplied by the factor λ , where—

λ = 1.0, for 0 < θ ≤ 15°; . . .5.2.2.2(1)

λ = (bcr cos2 θ)/sr, for 15° < θ ≤ 60°;

λ = 0, for θ > 60°; and

θ = the acute angle between the sheeting ribs and the longitudinal axis of

the steel beam (see Figure 5.2.2.2 including Note).

NOTE: The value of θ should be determined for each side of the beam where the orientation of the sheeting is

different.

FIGURE 5.2.2.2 EFFECTIVE WIDTHS OF CONCRETE PORTIONS OF

A COMPOSITE SLAB


35 AS 2327.1—2003


5.2.3 Effective portion of steel beam

5.2.3.1 General

The effective portion of the steel beam cross-section at the strength limit state shall be

determined in accordance with—

(a) Clause 5.2.3.2 if the entire depth of the steel beam is in tension; or

(b) Clause 5.2.3.3 if only part of the depth of the steel beam is in tension (see Note 1).

The part of the steel beam subject to tension at the strength limit state shall be determined

from Section 6.

For fabricated steel beams, or steel beams with an additional plate welded to the bottom

flange, the welds connecting the plate elements of the beam together shall be designed to

transmit the shear forces that develop on account of the axial tensile forces assumed to be

carried by these elements (see Note 2).

The effect of holing of the steel beam may be ignored in the following cases:

(i) Where holes are drilled in the top flange to accommodate high-strength structural

bolts used as shear connectors in accordance with Section 8.

(ii) Where holes are drilled or cut in the web so that their greatest internal dimension Lw

satisfies—

Lw/d1 ≤ 0.10 (see Note 3) . . . 5.2.3.1(1)

NOTES:

1 If there is partial shear connection at the cross-section of concern (i.e., β < 1), Item (b) will

always apply.

2 Particular attention needs to be given to this issue when designing cross-sections close to

where an additional plate welded to the bottom flange is terminated.

3 It is beyond the scope of this Standard to provide a method for designing composite beams

with larger web penetrations. A method for designing composite beams with larger web

penetration is given in Reference 9, Appendix I.

5.2.3.2 Tension in whole of steel beam (β = 1)

The whole of the steel beam section at a cross-section of a composite beam shall be

assumed to be effective.

5.2.3.3 Compression in part of steel beam (β ≤ 1)

When part of the top flange, or the top flange and part or all of the web of the steel beam is

in compression, account shall be taken of the slenderness (λe) of each of these plate

elements either partially or fully in compression, in order to determine the effective portion

of the steel beam (see Note 1). The plate element slenderness (λ e) is given by—

250

y

e

f

t

b

=λ . . . 5.2.3.3(1)

where

b = clear width of the element outstand from the face of the supporting

plate element or the clear width of the element between faces of

supporting plate elements

t = element thickness

fy = yield stress of plate element used in design


AS 2327.1—2003 36


Steel beams with slender plate elements shall not be used (see Note 1). The effective

portion of a steel beam with either compact (see Note 2) or non-compact (see Note 3) plate

elements shall be calculated according to the following:

(a) If the top flange and web are compact, the entire steel section shall be assumed to be

effective.

(b) If the outstand of the flange is non-compact, the effective flange width shall be the

maximum width for which the flange is compact.

(c) If the web is non-compact, the effective portion of the web may be determined in

accordance with Figure 5.2.3.3(a) in which the length ‘x’ is ineffective. Alternatively,

the effective portion of the web may be determined approximately as shown in

Figure 5.2.3.3(b) where the effective thickness of the effective web (t′w) is calculated

ignoring the ineffective portion of the web in the compressive zone. Cold-formed,

rectangular hollow steel sections, manufactured in accordance with AS 1163, shall

have a compact top flange, calculated in accordance with Table 5.1 and assuming a

uniform compressive stress distribution across the width of the flange.

NOTES:

1 It is assumed that the entire width of the bottom flange will be effective.

2 Slender plate elements are such that λe > λ ey, where values of the yield slenderness limit

λ ey are given in Table 5.1.

3 Compact plate elements are such that λ ep ≥ λe, where values of the plasticity slenderness

limit λep are given in Table 5.1.

4 Non-compact plate elements are such that λey ≥ λe > λep.

FIGURE 5.2.3.3 EFFECTIVE PORTION OF STEEL BEAM WITH

NON-COMPACT TOP FLANGE OR WEB


37 AS 2327.1—2003


TABLE 5.1

PLATE ELEMENT PLASTICITY AND YIELD SLENDERNESS LIMITS

Plasticity limit Yield limit Plate

element

Longitudinal

edges

supported

Residual

stresses

(see Notes) λλλλ ep Stress distribution λλλλ ey

Stress

distribution

Flange One

SR

HR

LW, CF

HW

10

9

8

8

16

16

15

14

Flange Both

SR

HR

LW, CF

HW

30

30

30

30

45

45

40

35

Web One any 82

115

Web Both any

For

1.0≥rp≥0.5:

)17.4(

111

p−r

For rp<0.5:

41/rp

For

1.0≥re≥0.5:

)16.3(

322

e+r

For re<0.5:

57.5/re

LEGEND:

SR = stress relieved

HR = hot-rolled or hot-finished

CF = cold-formed

LW = lightly welded

HW = heavily welded

NOTES:

1 Welded members with compressive residual stresses of less than 40 MPa may be considered to be lightly

welded.

2 The value of the parameter re, which defines the position of the elastic neutral axis, should be calculated from

the elastic stress distribution for the steel section alone, ignoring the presence of the concrete slab.

5.3 CALCULATION OF DESIGN ACTION EFFECTS DUE TO DESIGN LOADS

5.3.1 General

For the purpose of complying with the requirements for the strength limit state, the design

action effects in a simply supported composite beam and its connections shall be

determined using the calculation procedure in Clause 5.3.4.

NOTE: It is outside the scope of this Standard to provide rules for the design of the composite

beam if the steel beam is propped during Construction Stages 5 and 6 when it will act as a

continuous member.

5.3.2 Definitions

For the purpose of Clauses 5.3.3 to 5.3.5, the following definitions apply:

(a) Effective span the span used in the calculation of design action effects allowing for

different end support conditions of the composite beam (see Clause 5.3.3).

(b) Tributary area the plan area from which dead and live loads acting on the slab will

be assumed to be received by a supporting composite beam (see Clause 5.3.5).


AS 2327.1—2003 38


5.3.3 Effective span

The effective span of a composite beam (Lef) shall be taken as the distance between the

lines of action of the vertical reactions at the ends of the beam (where bending moment is

assumed to equal zero). When the lines of action of the beam reactions are unknown, their

position may be determined in accordance with Paragraph H1, Appendix H.

5.3.4 Calculation procedure

The composite beam shall be considered to be simply supported with an effective span Lef.

The design loads calculated in accordance with Section 4 shall be assumed to act over the

tributary area defined in Clause 5.3.5, taking into account the effect of any propping to the

slab. When calculating the design action effects for the composite beam, the effects of

construction sequence shall be ignored, whereby it shall be assumed that the design loads

are entirely resisted by the action of the composite beam.

NOTES:

1 It is assumed that at the strength limit state, the stresses in the composite beam section being

checked for strength are not affected by the sequence of construction or loading, and that they

can be calculated using rectangular stress block theory in accordance with Section 6.

2 If the capacity of a composite beam is being checked for Construction Stages 5 and 6, slab

propping may affect the tributary area determination; however, the design action effects M*

and V* are calculated without regard for the sequence of construction or loading.

3 If the capacity of a composite beam is being checked for the in-service condition, any

previous slab propping will neither affect the tributary area determination nor the calculation

of M* and V*.

5.3.5 Tributary area

In the absence of a more accurate determination, the tributary area of a composite beam for

the strength limit state may be determined in accordance with Paragraph H2, Appendix H.


39 AS 2327.1—2003


S E C T I O N 6 D E S I G N F O R S T R E N G T H

6.1 GENERAL

A composite beam shall be designed for strength in accordance with Clause 6.2 using the

effective section(s) determined in accordance with Section 5 and the degree of shear

connection (β) defined in Clause 1.4.3 and calculated as shown in Figure 6.1.

FIGURE 6.1 CALCULATION OF DEGREE OF SHEAR CONNECTION β AT

COMPOSITE BEAM CROSS-SECTION

6.2 DESIGN

6.2.1 General

The design shall be conducted to satisfy the limit state requirements specified in

Clause 6.2.2 following the procedure defined in Clause 6.2.3.

6.2.2 Limit state requirements

The composite beam shall be designed so that at every transverse cross-section—

(a) the design vertical shear capacity (φVu) is not less than the design vertical shear force

(V*) (i.e., φVu ≥ V*); and

(b) the design moment capacity (φMbv) is not less than the design bending moment (M*)

during construction and for the in-service condition (i.e. φMbv ≥ M*).

The above requirements shall be deemed to be satisfied at every cross-section if they are

shown to be satisfied at each of the relevant potentially critical cross-sections defined in

Clause 6.3.

6.2.3 Design procedure

6.2.3.1 General

A composite beam shall be designed for strength in accordance with either one of the

following, as appropriate:

(a) The general procedure given in Clause 6.2.3.3.


AS 2327.1—2003 40


(b) The simplified procedure given in Clause 6.2.3.2, only if—

(i) the beam is prismatic and uniformly loaded;

(ii) the mid-span cross-section satisfies the requirements for complete shear

connection; and

(iii) Mbc ≤ 2.5 Ms.

6.2.3.2 Simplified procedure

The simplified procedure for strength design is as follows:

(a) Calculate the effective section of the composite beam in accordance with Clause 5.2

assuming β = 0.

(b) Calculate the design action effects M* and V* at the mid-span cross-section and beam

ends, respectively, in accordance with Clause 5.3.

(c) Calculate the design vertical shear capacity (φVu) in accordance with Clause 6.4.1,

and check that φVu ≥ V* (see Clause 6.2.2(a)).

(d) Calculate the nominal moment capacity Mbc (and the corresponding value of Fcc) in

accordance with Paragraph D2.3.2, Appendix D and check that φMbc ≥ M*

(Clause 6.2.2(b)).

(e) Calculate the nominal shear capacity of a single shear connector (fvs) in accordance

with Section 8, and hence determine the minimum number of shear connectors (nic)

required between the mid-span cross-section and each end of the beam from the

following relationship (see Note 3 to Clause 6.2.3.3):

nic = Fcc / fds . . . 6.2.3.2

NOTE: This Equation only holds if all the shear connectors have the same design shear

capacity fds, otherwise the equation needs to be modified accordingly. Also, in accordance

with Clause 8.3.4, fds is a function of nic and hence the calculation of nic is an iterative

process.

(f) Distribute the shear connectors as uniformly as possible along the beam, satisfying

the detailing requirements in Clause 8.4 appropriate to the particular type and size of

shear connectors.

(g) Determine the quantity of longitudinal shear reinforcement in accordance with

Section 9.

Alternatively, the procedure given in Clause 6.2.3.3 may be followed.

6.2.3.3 General procedure

The general procedure for strength design is as follows:

(a) Identify all potentially critical cross-sections in accordance with Clause 6.3.

(b) Calculate the effective section at each potentially critical cross-section in accordance

with Clause 5.2.

(c) Calculate the design action effects M* and V* at each potentially critical cross-section

in accordance with Clause 5.3.

(d) For each potentially critical cross-section, calculate the design vertical shear capacity

(φVu) in accordance with Clause 6.4.1, check that φVu ≥ V* in accordance with

Clause 6.2.2(a) and calculate the value of the shear ratio γ (= V*/φVu).

(e) Identify those potentially critical cross-sections for which M* > 0 and the shear

ratio (γ) falls within the ranges—

(i) 0.0 ≤ γ ≤ 0.5; and

(ii) 0.5 < γ ≤ 1.0.


41 AS 2327.1—2003


(f) For the appropriate range and value of γ, calculate the relationship between

φMbv and β in accordance with Clause 6.4.2 at each corresponding potentially critical

cross-section (see Note 2).

(g) From Clause 6.5, calculate the minimum degree of shear connection (βi) at each

potentially critical cross-section (i) so that φMbv ≥ M* in accordance with

Clause 6.2.2(b), where φMbv and M* are the appropriate values at the particular

cross-section. The degree of shear connection at the cross-section of maximum

bending moment βm shall not be less than 0.5 (see Clause 6.6).

(h) With the values of βi determined from Step (g), calculate Fcp.i from Paragraph D2.3.3

of Appendix D with the applicable value of Fcc.i from Paragraph D2.3.2 for each

potentially critical cross-section (i).

(i) Calculate the nominal shear capacity of a single shear connector (fvs) in accordance

with Section 8, and hence determine the minimum number of shear connectors (ni)

required between each potentially critical cross-section for which M* > 0 and the

ends of the steel beam from the following relationship (see Note 3):

ni = Fcp.i/fds . . . 6.2.3.3(1)

(j) Distribute the shear connectors along the beam in accordance with Clause 6.6.

(k) Determine the required quantity of longitudinal shear reinforcement in accordance

with Section 9.

NOTES:

1 Use of the general design procedure is illustrated in Reference 1, Appendix I.

2 Mbv is the general symbol for nominal moment capacity either in the presence or absence of

vertical shear, and may be used to represent symbols such as Mb, and Mbc.

3 This Equation only holds if all the shear connectors have the same design shear capacity fds. If

not, the equation will need to be modified accordingly. Also, in accordance with Clause 8.3.4,

fds is a function of ni and hence the calculation of ni is an iterative process.

6.3 POTENTIALLY CRITICAL CROSS-SECTIONS

For the purpose of Clause 6.2.3.3, the following transverse cross-sections of a composite

beam shall be deemed to be potentially critical:

(a) Sections of maximum design bending moment (M*) and sections of maximum design

vertical shear force (V*).

NOTE: In the case of beams with a constant maximum moment region, the potentially

critical cross-sections with respect to bending are to be taken as those at the ends of the

constant moment region.

(b) Sections where external bending moments or concentrated vertical loads are applied

to the beam, for example where other beams frame into the composite beam.

(c) Sections where there is a change in the cross-sectional geometry of either the slab or

the steel beam, for example, at changes in flange width or thickness, at penetrations

in the web of the steel beam, or at a notched section.

(d) Sections midway between the section(s) of maximum design bending moment and the

adjacent end(s) of the beam where the nominal moment capacity (Mbc) corresponding

to complete shear connection exceeds 2.5 times the nominal moment capacity (Ms) of

the steel beam.


AS 2327.1—2003 42


6.4 CALCULATION OF DESIGN VERTICAL SHEAR CAPACITY (φφφφVu) AND

DESIGN MOMENT CAPACITY (φφφφMbv) AS A FUNCTION OF DEGREE OF SHEAR

CONNECTION (ββββ)

6.4.1 Design vertical shear capacity (φφφφVu)

Unless it can be demonstrated that the concrete slab contributes to the transverse shear

capacity of the composite beam, φVu shall be calculated in accordance with AS 4100,

assuming that only the steel beam is effective.

6.4.2 Design moment capacity (φφφφMbv)

The design moment capacity of a composite beam cross-section (φMbv) shall be calculated

as a function of the degree of shear connection (β) in accordance with—

(a) Appendix D (Paragraph D2) if γ ≤ 0.5; or

(b) Appendix D (Paragraph D3) if 0.5 < γ ≤ 1.

Prior to the full development of composite action during Construction Stage 5, i.e.

when 15≤ f′cj < f′c, the design moment capacity (φMbv) shall be calculated by replacing f′ c

with f′cj in all relevant equations in Appendix D, and using the appropriate value of φ given

in Table 3.1 depending on whether construction is propped or unpropped.

6.5 CALCULATION OF MINIMUM DEGREE OF SHEAR CONNECTION ββββi AT

POTENTIALLY CRITICAL CROSS-SECTIONS

6.5.1 General

The linear approximations to the φMbv−β relationships determined in accordance with

Clause 6.4 may be used to calculate the minimum degree of shear connection βi at a

potentially critical cross-section i in order to satisfy the strength requirement φMbv ≥ M*

(Clause 6.2.2(b)) at that cross-section. The appropriate equations are given in Clause 6.5.2

for cross-sections where γ ≤ 0.5, and in Clause 6.5.3 for cross-sections where γ > 0.5.

6.5.2 Cross-sections where γγγγ ≤≤≤≤ 0.5

At cross-sections where γ ≤ 0.5, the minimum degree of shear connection βi at each

potentially critical cross-section i may be calculated directly using any one of the following

equations, as appropriate, depending on the magnitude of design bending moment M* in

relation to the magnitudes of the design moment capacities φMs and φMb.5 (i.e., φMb at

β = 0.5) at the cross-section being considered (see Figure D2.2(b), Appendix D):

(a) For M* ≤ φMs

βi = 0

(b) For φMs < M* ≤ φMb.5

( ) 02

*

sb.5

s

i≥

−−

=MM

MM

φφφβ . . . 6.5.2(1)

(c) For φMb.5 < M* ≤ φMbc

( )b.5bc

b.5bc

i2

2*

MM

MMM

φφφφβ

−−+

= . . . 6.5.2(2)


43 AS 2327.1—2003


6.5.3 Cross-sections where 0.5 < γγγγ ≤≤≤≤ 1.0

At cross-sections where γ > 0.5, the minimum degree of shear connection (βi) at each

potentially critical cross-section i may be calculated directly using either of the following

equations, as appropriate, depending on the magnitude of design bending moment M* in

relation to the magnitudes of the design moment capacities φMbv.0, φMbv.ψ and φMbvc (i.e.,

φMbv at β = 0, ψ and 1.0, respectively) at the cross-section being considered (see

Figure D3.3(b), Appendix D):

(a) For 0 ≤ βi ≤ ψ

βi = ( ) ( )[ ]

( ) ( ) ( ) ( ) b.ψsbfcsf

ssf

12121221

1212*

MMMM

MMM

φγφγφγφγψφγφγ

−+−−−+−−−−−

. . . 6.5.3(1)

≥ 0

(b) For ψ < βi

βi = ( ) ( ) ( )[ ]

( )( )b.ψbc

bfcb.ψ

-12

1212*1

MM

MMM

φφγφγφγψ

ψ−

−−−−−+ . . . 6.5.3(2)

If the calculated value of βi is greater than 1.0, the section is inadequate.

6.6 DISTRIBUTION OF SHEAR CONNECTORS BETWEEN POTENTIALLY

CRITICAL CROSS-SECTIONS AND BEAM ENDS

6.6.1 General

Composite beams designed for strength using the general procedure in Clause 6.2.3.3 shall

have their shear connectors distributed in accordance with Clause 6.6.2.

For the purpose of Clause 6.6.2, the number of shear connectors (i

n′ ) considered fully

effective in contributing to the design moment capacity (φMbv) of potentially critical

cross-section i shall be calculated in accordance with Clause 6.6.3.

6.6.2 Distribution of shear connectors

The shear connectors shall be distributed longitudinally according to the following rules:

(a) The degree of shear connection at the cross-section of maximum design bending

moment (βm) shall not be less than 0.5. In the case of a beam with a constant

maximum moment region, this requirement shall only apply to the cross-section at the

middle of the region.

(b) The number of shear connectors (i

n′ ) considered to contribute to the design moment

capacity (φMbv) of potentially critical cross-section i shall equal or exceed ni, where ni

is determined from Clause 6.2.3.3.

(c) The shear connectors should be distributed as uniformly as possible between any

cross-section of maximum design bending moment (M*) and the adjacent end/s of the

beam, or between adjacent potentially critical cross-sections, as appropriate.

(d) The detailing requirements given in Clause 8.4 appropriate to the particular type and

size of shear connector used in the beam shall be satisfied.

6.6.3 Calculation of number of shear connectors (i

n′ )

The number of shear connectors (i

n′ ) considered to contribute to the design moment

capacity (φMbv) of potentially critical cross-section i shall equal the lesser number of

connectors provided on each side of the cross-section. This shall not exceed nic, where nic is

the minimum number of shear connectors required to develop complete shear connection at

cross-section i, ignoring the presence of shear force as given by Equation 6.2.3.2. Shear

connectors provided between any other potentially critical cross-section and a beam end, in


AS 2327.1—2003 44


excess of the number required to develop complete shear connection at that cross-section,

shall be ignored when calculating i

n′ .

NOTE: Particular attention should be paid to satisfying this latter requirement when the steel

beam is non-prismatic due to the presence of a notch, web penetration or flange plate. Then the

calculation is performed by successively considering segments of the beam between adjacent potentially critical cross-sections, moving out from a beam end as demonstrated by the example

in Figure 6.6.3.

NOTES:

1 PCC stands for potentially critical cross-section.

2 The number of shear connectors contributing to the design moment capacity at PCCs 3, 4 and 5 is

influenced by the reduced cross-sectional area of the steel beam at the web penetration.

3 It has been assumed that at least 25 connectors are effective and contribute to the design moment capacity

of the maximum moment cross-section on the right-hand side of PCC 5.

FIGURE 6.6.3 EXAMPLE SHOWING CALCULATION OF n′ i


45 AS 2327.1—2003


S E C T I O N 7 D E S I G N F O R S E R V I C E A B I L I T Y

7.1 GENERAL

Composite beams shall be designed for serviceability by limiting vertical deflection and

controlling cracking and vibration in accordance with Clauses 7.2 to 7.4 respectively.

7.2 DEFLECTION CONTROL

7.2.1 Definitions

For the purpose of this Section, the following definitions apply:

(a) Total deflection—the deflection arising from short-term and long-term loading effects

and shrinkage, which occurs from when the steel beam is erected until the end of the

design life.

NOTES:

1 If total deflection is measured from the top of the concrete slab, then it is zero at the point

in time when the slab is screeded level (i.e., during Construction Stage 3), in which case

it does not include any deflection from Construction Stages 1 to 3. Alternatively, total

deflection may be measured from the steel beam soffit relative to the horizontal, which

may be considered important when the floor is left visually exposed from beneath. In this

case, precambering the steel beam can reduce the total deflection.

2 For composite slabs, suggested upper limits for the deflection of the profiled steel

sheeting at the completion of Construction Stage 3 are given in Appendix C.

(b) Incremental deflection—the deflection arising from short-term and long-term loading

effects and shrinkage, which occurs after a chosen stage in the life of the structure

(e.g., after the attachment of brittle elements) up until the end of the design life.

7.2.2 Deflection control

The deflection of composite beams under in-service conditions shall be controlled as

follows:

(a) Limits for the calculated total and incremental deflection of the beam shall be chosen

appropriate to the structure and its intended use (see Note).

(b) The calculated deflections shall not exceed the chosen limits when the beam supports

the short-term and long-term design loads for serviceability determined in accordance

with Clause 4.1.4.

(c) The deflections of a beam shall be calculated using either a refined method in

accordance with Clause 7.2.3 or the simplified method in accordance with

Clause 7.2.4.

NOTE: Suggested upper limits for total and incremental deflections are given in Appendix C.

7.2.3 Refined method

A refined method of calculation shall make allowance for the following factors, as deemed

appropriate:

(a) Changes in beam section (i.e., steel beam or composite) during Construction Stages 1

to 6.

(b) Expected loading history during Construction Stages 1 to 6 and the in-service

condition.

(c) Changes in cross-section along the length of the beam.

(d) Flexural cracking and tension stiffening.


AS 2327.1—2003 46


(e) Creep and shrinkage of the concrete.

(f) Longitudinal slab reinforcement.

(g) Slip at the interface between the slab and the steel beam.

(h) Yielding in the steel beam (see Note).

(i) Residual stresses in the steel beam.

(j) Temperature changes.

(k) End restraints (axial or rotational or both).

(l) Precamber of the steel beam.

NOTE: This Standard permits localized yielding of the steel beam under serviceability loads

provided its effects are taken into account in the calculation of deflections.

7.2.4 Simplified method

The deflection may be calculated using the design procedure given in Appendix B, which

makes allowance for the following:

(a) Changes in beam section (i.e., steel beam or composite) during Construction

Stages 1 to 6.

(b) Expected loading history during Construction Stages 1 to 6 and the in-service

condition (see Note 1).

(c) Changes in cross-section along the length of the beam (see Note 2).

(d) Flexural cracking.

(e) Creep and shrinkage of the concrete.

(f) Slip at the interface between the slab and the steel beam.

(g) Precamber of the steel beam.

For composite beams incorporating a steel beam consisting of a cold-formed rectangular

hollow section manufactured in accordance with AS 1163, the immediate deflection

components calculated using the simplified method shall be increased by 20% (see Notes 3

and 4).

The simplified method shall not be used if the maximum stress in the steel beam (either

tensile or compressive), calculated ignoring residual stresses, exceeds 0.9 fyb either during

construction or under serviceability loads during the in-service condition.

NOTES:

1 The load combinations for the serviceability limit state assumed in the formulation of the

simplified method have been taken from AS/NZS 1170.0 as G + ψs Q and G + ψlQ during the

in-service condition.

2 Beams with holes drilled or cut in the web, where their greatest internal dimension Lw

exceeds Lw/d1 = 0.10, should not be designed using the simplified method.

3 This allowance is made to take into account the effects of factors including residual stresses

in the steel tubing and additional shear connection flexibility associated with local

deformations of the tube walls.

4 The additional deflections in composite beams incorporating cold-formed rectangular hollow

sections are reported in Reference 2, Appendix I.


47 AS 2327.1—2003


7.3 CRACK CONTROL

7.3.1 Slab continuity transverse to span

Cracking in the concrete flange of composite beams, which is due to continuity of the slab

transverse to the span of the beam, shall be deemed to be controlled if the requirements of

AS 3600 for crack control of slabs are satisfied for both the primary and secondary

directions.

7.3.2 Slab continuity in the direction of the span

Cracking in the concrete flange at the ends of simply-supported composite beams may

occur where there is continuity of the slab in the direction of the span at those locations

(e.g., where secondary beams frame into both sides of a primary beam). Appropriate

measures shall be taken to control or prevent such cracking, particularly where

minimization of crack widths is an important consideration (e.g., for durability of the floor

or satisfactory appearance of any applied floor finish).

NOTE: Accounting for the continuity of the slab beyond the beam support is outside the scope of

this Standard; however, the problem is normally avoided by using unpropped construction. Some

guidance on this matter is given in Reference 3, Appendix I.

7.4 VIBRATION CONTROL

The response of a floor system incorporating composite beams to an applied source of

vibration shall be controlled so that there will be—

(a) no damage to the beam or the structure of which it is a part;

(b) no unanticipated restrictions imposed on the intended use of the structure; and

(c) not more than minimal discomfort to the occupants of the structure.

The above requirements may be satisfied by means of the following, used either singly or in

combination:

(i) Dynamically isolating the applied source from the floor.

(ii) Limiting the frequencies of the relevant modes of vibration of the floor to values

significantly different to the anticipated excitation frequencies.

(iii) Ensuring that sufficient mass is mobilized in the relevant vibration modes such that

the acceleration response is limited to an acceptable level.

(iv) Providing sufficient damping to limit near-resonant acceleration response to an

acceptable level.

NOTE: Guidance on the design of floor systems for occupant-induced vibration is given in

References 4 and 10, Appendix I.


AS 2327.1—2003 48


S E C T I O N 8 D E S I G N O F S H E A R

C O N N E C T O R S

8.1 GENERAL

Shear connectors for attachment to the top flange of the steel beam shall comply with the

requirements of Clause 8.2. Their design shear capacity shall be determined from

Clause 8.3, and they shall be detailed in accordance with Clause 8.4. The strength grade of

the slab concrete shall not exceed 40 MPa.

NOTE: A limit is placed on the strength grade because shear connector ductility tends to reduce

as concrete compressive strength increases.

The shear connectors may be used in the presence of profiled steel sheeting. The profiled

steel sheeting shall be defined as either closed-rib or open-rib (see Clause 1.4.3) which can

affect the strength (see Clause 8.3.3) and the detailing of the shear connectors (see

Clause 8.4).

8.2 SHEAR CONNECTORS

8.2.1 Types

Shear connectors shall be limited to one or more of the following types (see also

Figure 8.2):

(a) Headed studs.

(b) Channels.

(c) High-strength structural bolts.

The geometry of each type of shear connector shall conform with Clause 8.2.2.


49 AS 2327.1—2003


DIMENSIONS IN MILLIMETRES

FIGURE 8.2 SHEAR CONNECTOR DETAILS

8.2.2 Geometry

8.2.2.1 Headed studs

Standard-type headed studs with a nominal shank diameter of either 15.9 mm or 19 mm

shall be used. They shall comply with the dimensions and tolerances given in AS 1554.2 for

this type of shear connector.

The minimum overall height of studs after welding, measured from the top of the stud to the

top surface of the top flange of the steel beam, shall be 4.0 times the nominal shank

diameter dbs. In composite slabs, the studs shall extend not less than 40 mm above the top of

the ribs of the profiled steel sheeting (see Figure 8.2 (a)).

8.2.2.2 Channels

Channel shear connectors shall be cut only from sections designated 100TFC or 100PFC in

AS/NZS 3679.1, and shall have a nominal length (l) of 50 mm. Their minimum and

maximum lengths shall be 50 mm and 60 mm, respectively (see Figure 8.2 (b)).

8.2.2.3 High-strength structural bolts

High-strength structural bolts shall be M20 in size and fitted with one nut above and one

below the top flange of the steel beam. After tightening, at least one clear thread shall show

above the top nut and at least one thread plus the thread run-out shall show below the

bottom nut. Washers may be omitted. The overall height of the bolts measured between the

top of the bolt head and the top surface of the flange of the steel beam shall not be less than

100 mm (see Figure 8.2 (c)).


AS 2327.1—2003 50


8.3 SHEAR CAPACITY OF SHEAR CONNECTORS

8.3.1 General

When cast in normal-weight or lightweight concrete, the nominal shear capacity (fvs) of

single shear connectors, of the types described in Clause 8.2.1, shall be determined from

Clause 8.3.2 for solid slabs and Clause 8.3.3 for composite slabs.

The design shear capacity (fds) of a shear connector acting either by itself or as an element

of a set of shear connectors shall be calculated in accordance with Clause 8.3.4.

8.3.2 Nominal shear capacity in solid slabs

8.3.2.1 Headed studs

The nominal shear capacity (fvs) of either an automatically welded or manually welded

headed stud shall be determined as the lesser value from the following equations:

fvs = uc

2

bs63.0 fd ; or . . . 8.3.2.1(1)

fvs = ccj

2

bs31.0 Efd ′ . . . 8.3.2.1(2)

where

fuc = characteristic tensile strength of shear-connector material, not to exceed

500 MPa when substituted into Equation 8.3.2.1(1)

Ec = elastic modulus of slab concrete corresponding to the relevant value of f′cj =

cj

1.5

c 043.0 f ′ρ

During Construction Stage 6 and the in-service condition, the values for the nominal shear

capacity (fvs) of headed-stud shear connectors in normal-weight concrete, of a standard

strength grade (f′c = 20, 25, 32 or 40 MPa), are as given in Table 8.1 for the standard shank

diameters of 15.9 mm and 19.0 mm.

During Construction Stage 5 (15 MPa ≤ f′cj < f′c), the value for fvs shall be calculated

either—

(a) as the lesser value directly from Equations 8.3.2.1(1) and 8.3.2.1(2) for both normal-

weight and lightweight concrete; or

(b) for normal-weight concrete, from Table 8.1 by linear interpolation between the values

of fvs in the two adjacent columns between which f′cj falls.

TABLE 8.1

NOMINAL SHEAR CAPACITY fvs OF HEADED-STUD SHEAR

CONNECTORS IN NORMAL-WEIGHT CONCRETE

fvs (kN) forcf ′ (MPa) of — Stud diameter

dbs (mm) fvs (kN) for

cjf ′ = 15 MPa 20 25 32 40

19.0 60 75 89 93 93

15.9 42 53 62 65 65

NOTE: The tabulated values of fvs have been calculated from Equations 8.3.2.1(1) and 8.3.2.1(2)

assuming ρc = 2400 kg/m3 and using the minimum value permitted by AS 1554.2 for fuc, which is

410 MPa.


51 AS 2327.1—2003


8.3.2.2 Channels


capacity (fvs) of channel shear connectors in normal-weight concrete, of a standard strength

grade (f′c = 20, 25, 32 or 40 MPa), shall be determined from Table 8.2.

During Construction Stage 5 (15 MPa ≤ f′cj < f′ c), the value for fvs in normal-weight

concrete shall be calculated from Table 8.2 by linear interpolation between the values of fvs

in the two adjacent columns between which f′ cj falls.

For channels in lightweight concrete, fvs shall be taken as 80% of the value determined

above for normal-weight concrete of the same grade.

TABLE 8.2

NOMINAL SHEAR CAPACITY fvs OF CHANNEL SHEAR CONNECTORS IN

NORMAL-WEIGHT CONCRETE

fvs (kN) for f′′′′ c (MPa) of— Size ×××× length/grade

fvs (kN) for

f′′′′ cj = 15 MPa 20 25 32 40

100 TFC × 50/250 76 95 100 110 125

100 PFC × 50/300 76 95 100 110 125



capacity (fvs) of M20 high-strength structural bolt shear connectors in normal-weight

concrete, of a standard strength grade (f′c = 20, 25, 32 or 40 MPa), shall be determined from

Table 8.3.

During Construction Stage 5 (15 MPa ≤ f′cj < f′ c), the value for fvs in normal-weight

concrete shall be calculated from Table 8.3 by linear interpolation between the values of fvs

in the two adjacent columns between which f′ cj falls.

For high-strength structural bolts in lightweight concrete fvs shall be taken as 80% of the

value determined above for normal-weight concrete for the corresponding strength.

TABLE 8.3

NOMINAL SHEAR CAPACITY fvs OF HIGH STRENGTH STRUCTURAL BOLT

SHEAR CONNECTORS IN NORMAL-WEIGHT CONCRETE

fvs (kN) for f′′′′ c (MPa) of— Size/grade dbs (mm)

fvs (kN) for

f′′′′ cj = 15 MPa 20 25 32 40

M20/8.8 20 67 83 98 118 126

NOTE: The tabulated values of fvs have been calculated from Equations 8.3.2.1(1) and 8.3.2.1(2) assuming

ρc = 2400 kg/m3 and using the maximum value permitted by AS 1252 for fuc, which is 500 MPa.

8.3.3 Nominal shear capacity in composite slabs

The nominal shear capacities (fvs) of the different types of shear connectors in composite

slabs shall be the same as those given in Clause 8.3.2 for solid slabs. When headed studs are

placed in pairs between sheeting ribs of an open-rib profile deemed perpendicular to the

steel beam, the value of fvs shall be determined from Clause 8.3.2.1 using a value of fuc of

not greater than 410 MPa.


AS 2327.1—2003 52


8.3.4 Design shear capacity

The design shear capacity (fds) of a shear connector acting as an element of set of n shear

connectors is given by—

vsndsfkf φ= . . . 8.3.4(1)

where the value of φ is given in Table 3.1, and the load-sharing factor (kn), given as a

function of n, is—

( )nk /18.018.1n

−= . . . 8.3.4(2)

The number of shear connectors (n) shall be taken as the lesser number of shear connectors

provided between each end of the beam and the cross-section being designed.

8.4 DETAILING OF SHEAR CONNECTORS

8.4.1 Longitudinal detailing

For beams with solid or composite slabs, the shear connectors shall be detailed along the

length of the beam according to the following requirements:

(a) Longitudinal distribution The shear connectors shall be longitudinally distributed

between potentially critical cross-sections and beam ends as uniformly as possible in

accordance with Clause 6.6, while complying with the longitudinal spacing

requirements of Clause 8.4.1(b).

(b) Longitudinal spacing limits The longitudinal spacing of shear connectors shall not

exceed 4.0 times the overall depth (Dc) of the slab, or 600 mm, whichever is the

lesser.

In solid slabs and in composite slabs with sheeting deemed parallel to the steel beam,

the longitudinal spacing shall be—

(i) not less than 5.0 times the shank diameter (dbs) of the shear connectors between

centres of headed studs or high-strength structural bolts, ignoring staggering

(see Figure 8.4.1(A)(a)); or

(ii) not less than 100 mm clear between adjacent edges of channels (see

Figure 8.4.1(A)(b)).


53 AS 2327.1—2003



FIGURE 8.4.1(A) LONGITUDINAL SPACING OF SHEAR CONNECTORS

IN SOLID SLABS

(c) Proximity to ribs of open-rib profiles Where the slab is composite with the profiled

steel sheeting ribs passing over the steel beam, and automatically welded headed

studs are used, the distance between adjacent faces of a shear connector and a

sheeting rib measured parallel to the longitudinal axis of the beam shall be not less

than 60 mm (see Figure 8.4.1(B)).

FIGURE 8.4.1(B) PLACEMENT OF AUTOMATICALLY WELDED HEADED STUDS IN

COMPOSITE SLABS INCORPORATING OPEN-RIB PROFILE WITH RIBS PASSING OVER

STEEL BEAM


AS 2327.1—2003 54


(d) Proximity to ribs of closed-rib profiles Where the slab is composite with the profiled

steel sheeting ribs passing over the steel beam, and automatically welded headed

studs are used, there shall be no restriction on the distance between adjacent faces of

a shear connector and a sheeting rib measured parallel to the longitudinal axis of the

beam.

NOTE: There should be sufficient clearance between adjacent faces of the steel sheeting rib

and the stud being welded to permit the ceramic ferrule used in the welding operation to fit

flat on the sheeting pan, and avoid any conflict of the welding gun with the steel rib.

8.4.2 Transverse detailing

Each transverse cross-section of the beam where shear connectors are placed shall be

detailed according to the following requirements:

(a) Maximum number of shear connectors per transverse cross-section or sheeting

pan The number of shear connectors per transverse cross-section (nx) shall not

exceed the maximum values given in Table 8.4 according to the type of shear

connector and whether the slab is solid or composite.

For composite slabs incorporating an open-rib profile with the sheeting ribs deemed

perpendicular to the steel beam (see Clause 9.4.2.2), and automatically welded headed

studs are fired through the sheeting, the tabulated values are the maximum number of

connectors permitted between any two consecutive ribs.

TABLE 8.4

MAXIMUM NUMBER OF SHEAR CONNECTORS PER CROSS-SECTION (nx)

Shear connector type Solid slab Composite slab

Automatically welded headed studs 3 2

Manually welded headed studs 3 2

High-strength structural bolts 2 2

Channels 1 1

(b) Transverse spacing of headed studs or high-strength structural bolts Headed studs

and high-strength structural bolts shall be spaced transversely so that the clear

distance between their heads is not less than 1.5 times the shank diameter of the shear

connector (dbs).

(c) Proximity to profiled steel sheeting Where the slab is composite, the minimum

clearance between the shear connector and the nearest part of a sheeting rib or end of

an open-rib profile shall be—

(i) for automatically welded headed studs, in accordance with Figure 8.4.2(a);

(ii) for manually welded headed studs and high-strength structural bolts, in

accordance with Figure 8.4.2(b) and (c); and

(iii) for channels, in accordance with Figure 8.4.2(d).

NOTE: For closed-rib profile steel sheeting, the limits on minimum distance in Figure 8.4.2

do not apply.


55 AS 2327.1—2003


Shear connector

type

Distance to sides of sheeting ribs

(mm)

Distance to ends of sheeting

(mm)

(a) Automatically

welded headed

studs

(i) Sheeting discontinuous with a gap

between sheets, and shear

connectors welded directly to the

steel beam

(ii) Sheeting discontinuous without a

gap between sheets, and shear

connectors welded through the

sheeting.

FIGURE 8.4.2(in part) TRANSVERSE DETAILING OF SHEAR CONNECTORS IN

PROXIMITY TO PROFILED STEEL SHEETING


AS 2327.1—2003 56


Shear connector

type

Distance to sides of sheeting ribs

(mm)

Distance to ends of sheeting

(mm)

(b) Manually welded

headed studs

(c) High-strength

structural bolts

(d) Channels

NOTE: For Cases (b), (c) and (d), the sheeting is discontinuous on both sides of the shear connector.

FIGURE 8.4.2(in part) TRANSVERSE DETAILING OF SHEAR CONNECTORS IN

PROXIMITY TO PROFILED STEEL SHEETING

8.4.3 Attachment details

8.4.3.1 General

For steel beams consisting of either an I, Tee, channel, or fabricated rectangular hollow

section, the thickness of the steel beam flange to which a welded stud or high-strength

structural bolt, as appropriate, is attached shall not be less than 0.4 times the shank diameter

of the shear connector (dbs), except that in the case of welded studs this restriction does not

apply if the studs are welded directly over the web. For channel shear connectors, the

thickness of flange to which it is welded shall be not less than 6 mm.


57 AS 2327.1—2003



FIGURE 8.4.3.1 SHEAR CONNECTOR MINIMUM EDGE DISTANCES

For steel beams consisting of a cold-formed rectangular hollow section manufactured in

accordance with AS 1163, not more than one shear connector shall be attached at a

transverse cross-section. The thickness of the section to which automatically welded studs

are to be attached shall be not less than 0.4dbs. Headed studs or channels may be manually

welded to cold-formed rectangular hollow sections not less than 4 mm in thickness.

The distance between the edge of a shear connector and the adjacent edge of the flange to

which it is connected shall be not less than that shown in Figure 8.4.3.1. These distances

may need to be increased to provide the required end bearing for the sheeting.

Headed studs shall be welded using either automatically timed stud welding equipment in

accordance with AS 1554.2 (i.e., ‘automatically welded studs’) or by manual fillet welding

in accordance with Clause 8.4.3.3 (i.e., ‘manually welded studs’). Only automatically-

welded studs may be welded through profiled steel sheeting in accordance with

Clause 8.4.3.2.


AS 2327.1—2003 58


8.4.3.2 Automatically welded headed studs

Automatically welded headed studs shall be welded in accordance with AS 1554.2. Studs

shall not be welded through longitudinal stiffeners.

NOTE: It follows from this requirement and from Clause 8.4.1(c) that, depending on the angle

between the sheeting ribs and the longitudinal axis of the steel beam, the studs may only be

placed in the central flat area of the sheeting pans of an open-rib profile, as shown in

Figure 8.4.1(B).

8.4.3.3 Manually welded headed studs

Manually welded headed studs shall be attached directly to the flange of the steel beam, and

not through profiled steel sheeting. The surface and stud base preparation, minimum fillet

size and the welding procedure for attaching headed studs shall be in accordance with

AS 1554.2.

NOTE: It is recommended that if a manual metal-arc welding procedure is adopted, then

3.25 mm E48XX electrodes should be used in a two-pass operation.

8.4.3.4 Channels

Channels shall be welded directly to the flange of the steel beam, and not through profiled

steel sheeting. The minimum weld details for attaching channels are shown in

Figure 8.2.2(b). Welding shall be carried out in accordance with AS/NZS 1554.1.


High-strength structural bolts shall be fitted into 20 mm finished diameter holes. The holes

shall be—

(a) round and be machine-flame cut;

(b) drilled full size;

(c) sub-punched 3 mm undersized and reamed to size; or

(d) punched full size.

A punched hole shall only be permitted in material whose yield stress fy does not exceed

360 MPa and whose thickness does not exceed 5600/fy mm. The minimum edge distance

shall comply with AS 4100.

The bolts shall be snug tight as defined in AS 4100.

All material between the nuts shall be steel, except that profiled steel sheeting, or any other

type of steel component, which may be compressible, shall not be permitted.

8.4.4 Minimum concrete cover for durability

For protection against corrosion of the shear connectors, the cover to the nearest concrete

surface shall be—

(a) to any unprotected edge of the slab, not less than 75 mm; and

(b) to the top surface of the slab, not less than the value given in Table 8.5 for the

appropriate concrete characteristic compressive strength f′c and exposure

classification defined in AS 3600.


59 AS 2327.1—2003


TABLE 8.5

MINIMUM TOP COVER TO SHEAR CONNECTORS

Exposure

classification

f′c = 20

MPa

25 32 40

A1 20 20 20 20

A2 — 25 20 20

B1 — — 30 25

B2 — — — 35


AS 2327.1—2003 60


S E C T I O N 9 T R A N S F E R O F L O N G I T U D I N A L

S H E A R I N C O N C R E T E

9.1 GENERAL

Sufficient longitudinal shear reinforcement shall be provided in the concrete flange to

prevent longitudinal shear failure of the flange arising from the transfer of longitudinal

forces through the shear connectors.

The reinforcement may be designed in accordance with Clause 9.3. Alternatively, the

reinforcement, including any contribution of the profiled steel sheeting, may be designed by

load testing two or more prototype beams in accordance with Clause 12.3, using appropriate

design loads determined from Clause 4.1.

NOTE: Throughout the Section it is assumed that all the shear connectors in a beam have the

same nominal shear capacity fvs. If this is not the case, the design procedure given in Clause 9.3.2

can be readily modified.

9.2 DEFINITIONS

For the purpose of this Section, the definitions below apply.

9.2.1 Connector group

The shear connectors grouped at a transverse cross-section of a beam.

9.2.2 Connector set

The shear connectors between a transverse cross-section and an end of a beam.

9.2.3 Longitudinal shear plane

A plane in a slab over which a longitudinal shear failure can potentially occur.

9.2.4 Longitudinal shear surface

A surface comprising either a single longitudinal shear plane, or two or more intersecting

longitudinal shear planes, over which a shear failure can possibly occur leading to part of

the concrete slab separating from the composite beam.

9.2.5 Longitudinal shear reinforcement

Reinforcement (not necessarily horizontal) that crosses one or more longitudinal shear

planes.

9.3 DESIGN

9.3.1 Limit state requirement

The longitudinal shear reinforcement in a slab shall be designed so that at any longitudinal

shear surface, the design longitudinal shear capacity per unit length of beam (φVL) shall not

be less than the design longitudinal shear force per unit length of beam (V*L)

(i.e., φVL ≥ V*L).

This requirement shall be deemed to be satisfied at every conceivable longitudinal shear

surface located within the effective width of a slab, provided it can be shown to be satisfied

at every occurrence of the relevant types of shear surfaces defined in Clause 9.4.1.

Reinforcement for Types 1, 2 and 3 longitudinal shear surfaces shall satisfy the

requirements of Clause 9.3.2. Reinforcement for Type 4 longitudinal shear surfaces shall

satisfy the requirements of Clause 9.8.


61 AS 2327.1—2003


9.3.2 Design procedure

For Types 1, 2 and 3 longitudinal shear surfaces, the longitudinal shear reinforcement in the

concrete slab of a composite beam shall be designed according to the following procedure

(see also Figure E4 of Appendix E):

(a) At each potentially critical transverse cross-section i of the beam identified at Step (e)

in Clause 6.2.3.3 at which M* > 0, determine the lesser number of shear connectors

(ni.min) that have been provided between the cross-section and the ends of the beam.

(b) Calculate the design shear capacity (fds) of the connectors in accordance with

Clause 8.3.4, based on the largest value of ni.min determined from Step (a) for all the

potentially critical transverse cross-sections. This value of fds shall be assumed for

every connector in the beam.

(c) Identify those regions along the length of the beam where there is a variation in either

the number of connectors per connector group (nx) or the longitudinal spacing

between adjacent connector groups (sc).

(d) Calculate values of the total design longitudinal shear force per unit length (V*L.tot)

corresponding to the value of fds and the different values of nx and sc determined from

Steps (b) and (c) using the relationship—

c

dsx

L.tot*

s

fnV = . . . 9.3.2

(e) Identify the different types of longitudinal shear surfaces defined in Clause 9.4.1

applicable to each situation being designed, i.e., each combination of nx and sc with

its corresponding value of V*L.tot, and calculate the shear surface perimeter length (u)

for each case in accordance with Clause 9.4.2. Any other cross-sectional differences,

such as a change in the transverse spacing between connectors, shall also be taken

into account.

(f) Calculate the design longitudinal shear force per unit length (V*L) acting on each

longitudinal shear surface applicable to each situation being designed in accordance

with Clause 9.5.

(g) Calculate the cross-sectional area of the longitudinal shear reinforcement (Asv)

required at each shear surface in longitudinal shear so that φVL ≥ V*L in accordance

with Clause 9.3.1, where the nominal longitudinal shear capacity per unit length (VL)

shall be calculated in accordance with Clause 9.6, and the value of the capacity factor

φ is given in Table 3.1.

(h) Detail the longitudinal shear reinforcement in accordance with Clause 9.7.

9.4 LONGITUDINAL SHEAR SURFACES

9.4.1 Shear surface types

For determining longitudinal shear transfer, four types of longitudinal shear surfaces shall

be considered in design (see Figure 9.4.1) as follows:

(a) Type 1 A plane that passes directly through the concrete in a solid or composite slab

at right angles to its top surface.

(b) Type 2 A combination of three orthogonal planes, which enclose the shear

connectors in a solid or composite slab, two of which emanate from the slab bottom

face.

(c) Type 3 A combination of three planes, which enclose the shear connectors in a

composite slab, either one or two of which emanate from the top corners of the steel

sheeting ribs which cross the transverse cross-section.


AS 2327.1—2003 62


(d) Type 4 A horizontal plane that passes across the tops of the steel sheeting ribs in a

composite slab in which the sheeting ribs are deemed perpendicular to the beam,

locally avoiding the shear connectors by passing over their tops, and which extends

from the outside vertical face of a slab outstand in a composite edge beam and

continues some distance into the adjacent slab.

NOTE: Type 4 longitudinal shear failure is described in Reference 5, Appendix I.


FIGURE 9.4.1 LONGITUDINAL SHEAR SURFACE TYPES


63 AS 2327.1—2003


9.4.2 Shear surface perimeter length (u)

9.4.2.1 General

The length of the perimeter (u) of the intersection between a Type 1, 2 or 3 longitudinal

shear surface and a transverse slab cross-section shall be determined in accordance with this

Clause.

9.4.2.2 Orientation of profiled steel sheeting

The orientation of profiled steel sheeting as it affects the perimeter length of Type 1 and

Type 3 shear surfaces shall be taken into account as follows (see also Figure 5.2.2.2):

(a) When the acute angle θ between the steel ribs and the longitudinal axis of the steel

beam is less than or equal to 15°, the sheeting shall be deemed to be parallel to the

beam.

(b) When θ exceeds 15°, the sheeting shall be deemed to be perpendicular to the beam.

9.4.2.3 Type 1 shear surfaces

At least the following occurrences of Type 1 shear surfaces shall be considered in design

(see Figure 9.4.2.3):

(a) At the outside faces of shear connector groups.

(b) Where longitudinal shear reinforcement is curtailed.

(c) Directly over each steel sheeting rib deemed parallel to the steel beam in accordance

with Clause 9.4.2.2(a).

The perimeter length of Type 1 shear surfaces shall be assumed to equal one of the

following as appropriate:

(i) Dc for solid slabs.

(ii) Dc for composite slabs with sheeting ribs deemed perpendicular to the steel

beam.

(iii) (Dc−hr) directly over ribs for composite slabs with sheeting ribs deemed parallel

to the steel beam.

(iv) Dc between ribs for composite slabs with sheeting ribs deemed parallel to the

steel beam.


The perimeter length of Type 2 shear surfaces shall be assumed to equal (bx + 2hc), where—

bx = the overall width across the tops of all the shear connectors in the cross-

section (see Figure 9.4.1(a)); and

hc = the overall height of the shear connectors above the top flange of the

steel beam.


AS 2327.1—2003 64


FIGURE 9.4.2.3 LOCATIONS OF TYPE 1 SHEAR SURFACES


65 AS 2327.1—2003



The perimeter length of Type 3 shear surfaces shall be assumed to equal the lesser of the

values shown in Figure 9.4.2.5.

FIGURE 9.4.2.5 POSSIBLE PERIMETER LENGTHS OF TYPE 3 SHEAR SURFACES

9.5 DESIGN LONGITUDINAL SHEAR FORCE (V*L)

At a cross-section of a composite beam, the design longitudinal shear force per unit length

(V*L) shall be assumed to vary linearly from a maximum on each side of the centre-line of

the steel beam to zero at the extremities of the effective width of the concrete slab (see

Figure 9.5).

Accordingly, the design longitudinal shear force per unit length (V*L), acting on a Type 1,

shear surface centred distance x from an extremity of the effective width, shall be

determined from Equation 9.5(1) and on Types 2 and 3 surfaces from Equation 9.5(2).

L.tot

cf

L** V

b

xV

= . . . 9.5(1)

L.totL** VV = . . . 9.5(2)


AS 2327.1—2003 66


FIGURE 9.5 DISTRIBUTION OF LONGITUDINAL SHEAR FORCE FOR TYPE 1 SHEAR SURFACES

9.6 NOMINAL LONGITUDINAL SHEAR CAPACITY (VL)

The nominal longitudinal shear capacity per unit length (VL) of a Type 1, 2 or 3 shear

surface shall be calculated as the lesser value given by the following equations:

(a) VL = u(0.36 √f′c) + 0.9Asv fyr . . . 9.6(1)

(b) VL = 0.32 f′c u . . . 9.6(2)

where

u = shear surface perimeter length in millimetres, determined in

accordance with Clause 9.4.2

f′ c = characteristic compressive strength of the concrete, in megapascals

Asv = total cross-sectional area of longitudinal shear reinforcement crossing

the shear surface (see Figure 9.4.1(a)), in mm2 per mm length of beam

fyr = the yield strength of the longitudinal shear reinforcement, in

megapascals

Profiled steel sheeting shall not be considered to contribute to Asv.

NOTE: The units of VL determined from the above equations are newtons per millimetre length of

beam. Designers should ensure that V*L and φVL are expressed in the same units when comparing

them for the purpose of satisfying Clause 9.3.1.


67 AS 2327.1—2003


9.7 TYPES 1, 2 AND 3 LONGITUDINAL SHEAR REINFORCEMENT

9.7.1 General

The longitudinal shear reinforcement that crosses a Type 1, 2 or 3 shear surface shall be

detailed as follows:

(a) The cross-sectional area per metre length of beam (Asv) shall not be less than that

required by Clause 9.3.2, except that for Type 2 and Type 3 shear surfaces, neither

shall the area be less than that required by Clause 9.7.2. The reinforcement required

for each connector group shall be placed on either or both sides of the connectors of

that group within a distance sc /2 measured along the beam.

(b) It shall be anchored beyond the appropriate sides of the shear surface in accordance

with Clause 9.7.3.

(c) Its top face shall be at least 30 mm below the top of the shear connectors in the case

of Type 2 and Type 3 shear surfaces (see Figure 9.4.1(a)).

Flexural reinforcement in the slab placed transverse to the longitudinal axis of the beam

may be included as part or all of the reinforcement for longitudinal shear transfer, provided

that it meets all of these requirements as necessary.

9.7.2 Minimum longitudinal shear reinforcement for Type 2 and 3 shear surfaces

The minimum cross-sectional area of longitudinal shear reinforcement required for shear

transfer (Asv.min) across Type 2 and 3 shear surfaces, in square millimetres per metre length

of beam, shall be calculated according to the following equation:

yrfuA /800

sv.min= . . . 9.7.2

NOTE: The area of bottom bars (Asp.b) is required to be not less than Asv.min/2, as indicated in

Figure 9.4.1(a).

9.7.3 Anchorage of longitudinal shear reinforcement

Longitudinal shear reinforcement should extend beyond each side of the shear plane for at

least the development length for tension (Lsy.t) determined in accordance with AS 3600. If

the distance available for anchorage (L) is less than Lsy.t, the area of longitudinal shear

reinforcement considered to be effective for use in Equation 9.6(1) shall be taken as

AsvL/Lsy.t. In no case shall L be less than 15 db for straight deformed bars, where db is the

nominal diameter of the bar.

9.8 TYPE 4 LONGITUDINAL SHEAR REINFORCEMENT

9.8.1 Locations

Reinforcement for Type 4 shear surfaces shall be provided in edge beams with profiled steel

sheeting deemed perpendicular to the steel beam in accordance with Clause 9.4.2.2 and

which extends across the top flange of the steel beam (see Figure 9.4.1(b)), at locations

where there are—

(a) two welded stud shear connectors in a sheeting pan, irrespective of the width of the

slab outstand; or

(b) one welded stud shear connector in a sheeting pan, and the slab outstand is less than

600 mm wide measured from the vertical outside edge of the slab to the edge of the

nearest shear connector.


AS 2327.1—2003 68


9.8.2 Detailing

Longitudinal shear reinforcement provided at the locations specified in Clause 9.8.1 and

detailed in accordance with the following shall be deemed to develop the required

resistance across Type 4 shear surfaces. Alternative detailing may be used provided that it

can be demonstrated, by adequate test data, that the alternative prevents this mode of

failure.


FIGURE 9.8.2 TYPE 4 LONGITUDINAL SHEAR REINFORCEMENT


69 AS 2327.1—2003


The reinforcement shall satisfy all of the following:

(a) The reinforcement shall cross the shear surface and be composed of one or more of—

(i) stirrups or ties, which cross perpendicular to the shear surface and enclose

longitudinal bars; and

(ii) welded-wire fabric, with the longitudinal wires cranked such that they make an

angle of between 30° and 90° with the shear surface.

(b) The maximum transverse spacing of consecutive parallel bars or wires which form the

stirrups, ties or fabric shall be 150 mm measured perpendicular to the length of the

beam (see Figure 9.8.2).

(c) Reinforcement, of nominal tensile capacity (fyrAsv) not less than 20 kN per bar or

wire, shall be used. At each location, at least two such bars or wires shall cross the

shear surface every 150 mm width of slab. The reinforcement shall extend into the top

and bottom of the slab above and below the shear surface, respectively, and be

adequately anchored to develop a stress of at least 0.5fyr in the reinforcement at the

level of the shear surface. A width of slab at least equal to 400 mm shall be

reinforced. The reinforcement shall be centred over the steel beam, except that when

the slab outstand width is too narrow for this to occur, it shall be placed as close to

the slab edge as concrete covers will allow.

NOTE: Detailing of Type 4 longitudinal shear reinforcement is described in Reference 6,

Appendix I.


AS 2327.1—2003 70


S E C T I O N 1 0 D E S I G N F O R F I R E

R E S I S T A N C E

10.1 REQUIREMENTS

This Section applies to composite beams, with either a solid or composite slab, required to

have a fire-resistance level (FRL).

For protected composite beams, the thickness of protection material (hi) shall be not less

than that required to attain the period of structural adequacy (PSA) specified by the

required FRL.

For unprotected composite beams, the exposed surface area to mass ratio (ksm) shall be not

greater than that required to attain the PSA specified by the required FRL.

The period of structural adequacy (PSA) for a composite beam shall be determined in

accordance with Clause 10.3.

Connections and web penetrations shall be designed and constructed so that the fire-

resistance level of the composite beam is not impaired. This may be achieved by complying

with the requirements of Clause 10.9.

10.2 DEFINITIONS

For the purpose of this Section, the definitions below apply.

10.2.1 Exposed surface area to mass ratio

The ratio of the surface area exposed to the fire to the mass of steel, noting that in the case

of members with fire protection material applied, the exposed surface area is to be taken as

the internal surface area of the fire protection material.

10.2.2 Fire exposure condition

(a) Three-sided fire exposure condition A composite beam in which the top face of the

steel beam is in contact with a solid or composite slab in a specific configuration (see

Clause 10.8).

(b) Four-sided fire exposure condition A steel member or element exposed to fire on all

sides.

10.2.3 Fire protection system

The fire protection material and its method of attachment to the composite member.

10.2.4 Fire-resistance level (FRL)

The fire-resistance periods for structural adequacy, insulation and integrity, expressed in

that order in minutes, which are specified by the authority for the member or element.

10.2.5 Fire-resistance period

The elapsed time, in minutes, for a prototype member, or element of building construction,

to reach the relevant failure criterion specified in AS 1530.4, when tested in accordance

with that Standard.

10.2.6 Insulation

The ability of a fire separating member to limit the surface temperature on one side of the

member when exposed to fire on the opposite side.


71 AS 2327.1—2003


10.2.7 Integrity

The ability of a fire separating member to resist the passage of flames or hot gases through

the member when exposed to fire on one side.

10.2.8 Period of structural adequacy (PSA)

The time (t), in minutes, for the member to reach the limit state of structural adequacy.

10.2.9 Prototype

A test specimen representing a member and its fire protection system, which is subjected to

the standard fire test.

10.2.10 Standard Fire Test

The fire-resistance test specified in AS 1530.4.

10.2.11 Stickability

The ability of the fire protection system to remain in place as the member deflects under

load during a fire test, as specified in AS 1530.4.

10.2.12 Structural adequacy

The ability of the member to maintain its structural function when exposed to fire.

10.3 DETERMINATION OF PERIOD OF STRUCTURAL ADEQUACY

The period of structural adequacy (PSA) shall be determined using one of the following

methods:

(a) By calculating—

(i) the limiting temperature of the steel (Tl) in accordance with Clause 10.4; and

(ii) the PSA as the time from the start of the test (t) to the time at which the

limiting steel temperature is attained in accordance with Clause 10.5 for

protected members and Clause 10.6 for unprotected members.

(b) By direct application of a single test in accordance with Clause 10.7.

(c) By other calculation methods as defined in Clause 10.10.

10.4 DETERMINATION OF LIMITING TEMPERATURE OF THE STEEL

The limiting temperature of the steel Tl shall be calculated as follows:

fl690905 rT −= . . . 10.4

where

rf = the maximum value along the length of the beam of the ratio of the design

bending moment (M*), under the design load for fire, to the design moment

capacity (φMbv) at room temperature


ATTAINED FOR PROTECTED MEMBERS

10.5.1 Methods

The time (t) at which the limiting temperature (Tl) is attained shall be determined by

calculation on the basis of a suitable series of fire tests in accordance with Clause 10.5.2 or

from the results of a single test in accordance with Clause 10.5.3.


AS 2327.1—2003 72


10.5.2 Temperature based on test series

10.5.2.1 Method of calculation

Calculation of the variation of steel temperature with time shall be by interpolation of the

results of a series of fire tests using the regression analysis equation specified in

Clause 10.5.2.2 subject to the limitations and conditions of Clause 10.5.2.3.

10.5.2.2 Regression analysis

The relationship between temperature (T) and time (t) for a series of tests shall be

calculated by least-squares regression as follows:

+

+++

++=

sm

6

sm

i

5i43

sm

i

2il0k

Tk

k

ThkThkTk

k

hkhkkt . . . 10.5.2.1

where

t = time from the start of the test, in minutes

k0 to k6 = regression coefficients

hi = thickness of fire protection material, in millimetres

T = average steel temperature calculated using all thermocouples as shown in the

figure illustrating ‘Recommended location of thermocouples on typical

structural sections’ in AS 1530.4, in degrees Celsius, T > 250°C

ksm = exposed surface area to mass ratio, in square metres per tonne (m2 /t).

10.5.2.3 Limitations and conditions on use of regression analysis

Test data to be utilized in accordance with Clause 10.5.2.1 shall satisfy the following:

(a) Tested prototypes shall be protected with board, sprayed, blanket or similar insulation

materials having a dry density less than 1000 kg/m3.

NOTE: There is insufficient test data available to make comprehensive recommendations on

interpolation for members protected with other materials such as intumescent coatings.

(b) All prototypes shall be protected with the same fire protection system.

(c) All prototypes shall have the same fire exposure condition and shall fall within a

single group as defined in Clause 10.8.

(d) The test series shall include at least nine tests.

(e) The test series may include prototypes that have not been loaded provided that

stickability has been demonstrated.

The steel temperature for a composite beam may be obtained from a regression equation

provided that—

(i) the fire protection system is the same as that of the test series;

(ii) the fire exposure condition is the same as that of the test series;

(iii) the temperature can be obtained by interpolation within the window defined by the

test series as shown in Figure 10.5.2.3; and

(iv) the data is obtained from either steel or composite member prototypes.

The regression equation obtained for one fire protection system may be applied to another

system using the same fire protection material and the same fire exposure condition

provided that stickability has been demonstrated for the second system.


73 AS 2327.1—2003


A regression equation obtained using prototypes with a four-sided fire exposure condition

may be conservatively applied to a composite beam provided that stickability has been

demonstrated for the three-sided fire exposure condition.

FIGURE 10.5.2.3 DEFINITION OF WINDOW FOR INTERPOLATION LIMITS

10.5.3 Temperature based on single test

The variation of steel temperature with time measured in a single Standard Fire Test may be

used without modification provided—

(a) the fire protection system is the same as the prototype;

(b) the fire exposure condition is the same as the prototype;

(c) the fire protection material thickness is equal to or greater than that of the prototype;

(d) the exposed surface area to mass ratio is equal to or less than that of the prototype;

and

(e) where the prototype has been submitted to a Standard Fire Test in an unloaded

condition, stickability has been separately demonstrated.


ATTAINED FOR UNPROTECTED MEMBERS

The time (t) at which the limiting temperature is attained shall be calculated using the

following expression:

++−=

sm

433.00221.02.5

k

TTt . . . 10.6(1)


AS 2327.1—2003 74


where

t = time from the start of the test, in minutes

T = steel temperature, in degrees Celsius, 500°C ≤ T ≤ 750°C

ksm = exposed surface area to mass ratio, in square metres per tonne, 2 ≤ ksm ≤ 35

For temperatures below 500°C, linear interpolation shall be used based on the time at 500°C

and an initial temperature of 20°C at t = 0.

10.7 DETERMINATION OF PSA FROM A SINGLE TEST

The period of structural adequacy (PSA) determined in accordance with AS 1530.4 from a

single test may be applied without modification provided—

(a) the fire protection system is the same as the prototype;

(b) the fire exposure condition is the same as the prototype;

(c) the fire protection material thickness is equal to or greater than that of the prototype;

(d) the exposed surface area to mass ratio is less than or equal to that of the prototype;

(e) the conditions of support are the same as the prototype and the restraints are not less

favourable than those of the prototype; and

(f) the value of rf of the member (see Clause 10.4) is less than or equal to that of the

prototype.

10.8 THREE-SIDED FIRE EXPOSURE CONDITION

Beams subject to a three-sided fire exposure condition shall be considered elements of a

single group when both of the following conditions are satisfied:

(a) 1.25 groupinlowest

groupinhighest:densityconcreteFor ≤

(b) ( ) 25.1group in smallest

group in largest:depth slabFor

c≤

D

Blocking of rib voids in profiled steel sheeting which passes over the steel beam may be

ignored for grouping purposes.

10.9 CONNECTIONS AND WEB PENETRATIONS

10.9.1 Connections

Connections shall be protected with the maximum thickness of fire protection material

required for any of the members framing into the connection, to achieve their respective fire

resistance levels. This thickness shall be maintained over all connection components,

including bolt heads, welds and splice plates.

10.9.2 Web penetrations

The thickness of fire protection material at and adjacent to web penetrations (see

Figure 10.9.2) shall be the greatest of—

(a) that required for the area above the penetration considered as a three-sided fire

exposure condition (ksm1);

(b) that required for the area below the penetration considered as a four-sided fire

exposure condition (ksm2); or

(c) that required for the section as a whole considered as a three-sided fire exposure

condition (ksm).


75 AS 2327.1—2003


This thickness shall be applied over the full beam depth and shall extend each side of the

penetration for a distance at least equal to the steel beam depth and not less than 300 mm.

FIGURE 10.9.2 WEB PENETRATIONS

10.10 DETERMINATION OF PERIOD OF STRUCTURAL ADEQUACY BY

OTHER CALCULATION METHODS

The period of structural adequacy of a composite beam may be predicted by a suitable

method of calculation which takes into account the following:

(a) The variation of the mechanical properties of steel with temperature in accordance

with AS 4100.

(b) The variation of the mechanical properties of concrete and of steel reinforcement with

temperature in accordance with AS 3600.

(c) The temperature distribution in the member obtained from a rational method of

analysis confirmed by test data.


AS 2327.1—2003 76


S E C T I O N 1 1 C O N S T R U C T I O N

11.1 GENERAL

The requirements of this Section, where appropriate, shall be satisfied for each of the six

construction stages defined in Clause 4.2. Due allowance shall be made for differential

deflections between structural elements to avoid uncertain load distributions, possible

damage, or undue distortion.

11.2 CONSTRUCTION SEQUENCE AND LOADS

The construction sequence shall conform to that detailed on the drawings or in the project

specification (see Clause 1.6.2). It shall be assured during all stages of construction that the

live loads (including stacked materials) do not cause a more adverse effect on the structure

than that assumed in design (see Clause 4.2).

11.3 STEELWORK

11.3.1 Fabrication and erection

Fabrication and erection of steelwork shall be in accordance with AS 4100.

11.3.2 Site fixing of shear connectors

Site fixing of shear connectors shall comply with the following:

(a) The thickness of the steel flange shall satisfy the requirements of Clause 8.4.3.1.

(b) The distance between the edge of a shear connector, and either the end or the side of

an adjacent steel rib of an open-rib profile, shall be not less than as shown in

Figure 8.4.2.

NOTE: For closed-rib profiles see Note to Clause 8.4.1(d).

(c) The surface of the parent material, in the areas to which the shear connectors are to be

welded, shall be free of scale, rust, moisture, paint, mud, sand, grease or other

injurious material to the extent necessary to obtain satisfactory welds. The suitability

of the surface conditions for stud welding shall be assessed in accordance with the

requirements of AS 1554.2.

NOTE: A thin film of manganese zinc silicate paint may be acceptable.

(d) Automatic stud welding procedures through profiled steel sheeting shall be in

accordance with AS 1554.2. Studs shall not be welded through longitudinal stiffeners

and ceramic ferrules shall not come into contact with the stiffeners or sheeting ribs

during the welding operation.

(e) The different types of shear connectors shall be attached in accordance with

Clause 8.4.3. In particular, their proximity to profiled steel sheeting shall be in

accordance with Clause 8.4.

11.4 FORMWORK AND FALSEWORK

11.4.1 General

The arrangement of falsework shall take account of the deflections of the steel beams

during concreting to prevent undue distortion of the slab soffit.


77 AS 2327.1—2003


Removal of slab formwork/falsework and props to beams shall not commence until the

concrete has attained a characteristic compressive strength f′ cj of 15 MPa, i.e., end of

Construction Stage 4 (see Clause 4.2). The minimum period of time before stripping forms

or removing props shall be not less than that given in the project drawings or specification.

All dirt, excess water, ceramic ferrules and other deleterious matter accumulated during

construction shall be removed from the top surface of the formwork prior to concrete

placement. Oil shall not come into contact with the surface of profiled steel sheeting.

11.4.2 Solid slabs

Formwork and falsework for solid slabs shall comply with AS 3610.

11.4.3 Composite slabs

The manufacturer’s recommendations regarding the installation of profiled steel sheeting

shall be followed. The maximum deflection of the sheeting while it supports the plastic

concrete shall not exceed the value assumed in design.

NOTE: Suggested limits are given in Appendix C, Paragraph C2.

11.5 REINFORCEMENT

Reinforcement shall be supplied and fixed in accordance with AS 3600.

NOTE: When fabricating and placing the transverse reinforcement, special attention should be

given to the detailing requirements of Clause 9.7.1.

11.6 CONCRETE

11.6.1 Materials, manufacture and delivery

Concrete materials, manufacture and delivery shall be in accordance with AS 1379

including quality assessment for concrete as supplied.

11.6.2 Concrete after delivery

Handling, placing, compacting, curing and protection of plastic concrete after delivery shall

be in accordance with AS 3600, including determination of in situ strength at various stages

of construction.

11.7 FIRE PROTECTION MATERIAL

Sprayed mineral coatings shall be applied to the members in accordance with AS 3784.1.

Other fire protection materials shall be installed in accordance with the manufacturer’s

recommendations.


AS 2327.1—2003 78


S E C T I O N 1 2 L O A D T E S T I N G

12.1 GENERAL

12.1.1 Purpose of testing

Beams designed by calculation in accordance with other parts of this Standard are not

required to be tested. Tests may be accepted as an alternative to calculation, or may become

necessary in special circumstances, in order to satisfy the requirements of Clause 3.3.1 with

respect to strength and Clause 3.3.2 with respect to deflection.

Beams may be either—

(a) proof tested in accordance with Clause 12.2 to ascertain the structural characteristics

of an existing structure, substructure or individual member; or

(b) prototype tested in accordance with Clause 12.3, to ascertain the structural

characteristics of a particular class of beams which are nominally identical to the

beams tested.

12.1.2 Test set-up

All measuring equipment shall be calibrated and chosen to suit the range of measurements

anticipated in order to obtain accurate results. Care shall be exercised to ensure that no

artificial restraints are applied to a test specimen. All necessary precautions shall be taken

to prevent the collapse of any part of a structure being proof tested.

NOTE: In the case of prototype testing, it is suggested that if the details of the end connections

are also known, then the beams should also be tested with their connections.

12.1.3 Test load

The test load shall simulate the design loads for the relevant limit states. The test load shall

be applied gradually at a rate as uniform as practicable and without impact. The distribution

and duration of forces applied in the test shall represent those forces to which the structure

is deemed to be subjected under the requirements of Section 4.

12.1.4 Test deflections

The maximum vertical deflections of the beam shall be measured with respect to an

appropriate datum. Deflections shall, as a minimum requirement, be recorded at the

following times:

(a) During the application of the test load.

(b) Immediately the full test load has been applied.

(c) Immediately prior to removing the test load.

(d) After the removal of the test load.

12.2 PROOF TESTING

12.2.1 Test procedures

A proof test shall be conducted according to the following procedures:

(a) Before applying any load, record the original position of the members involved.

(b) Apply the test load for the relevant limit state, as determined from Clause 4.1.4.

(c) Maintain the test load for the necessary period.

(d) Remove the test load.


79 AS 2327.1—2003


12.2.2 Criteria for acceptance

Criteria for acceptance shall be as follows:

(a) Acceptance for strength The test structure, substructure or beam shall be deemed to

comply with the requirements for strength if it is able to sustain the strength limit

state test load for at least 24 h without incurring any significant damage.

(b) Acceptance for deflection The maximum deflection of any beam under the

serviceability limit state test load shall be within the serviceability limits appropriate

to the structure.

12.2.3 Damage incurred during test

The tested members and their end connections shall be regularly inspected to determine the

nature and extent of any damage incurred during the test. The effects of the damage shall be

considered and the test disbanded if collapse seems likely. At the completion of the test,

appropriate repairs to damaged parts shall be carried out.

12.3 PROTOTYPE TESTING

12.3.1 Construction of prototypes

The prototype beams shall be constructed from materials that comply with Section 2. Any

additional requirements of a manufacturing specification shall also be complied with.

12.3.2 Number of prototypes

The number of prototypes to be tested should be selected so that statistically reliable

estimates for the strength or deflection, or both, of the design member can be determined

from the results of the tests, but in any case not fewer than two prototypes shall be tested.

12.3.3 Test loads

The test loads shall be adjusted so that the total load on each prototype is equal to the

design load for the relevant limit state as determined from Clause 4.1.4, multiplied by the

appropriate factor given in Table 12.1, corresponding to the number of prototypes to be

tested, unless a reliability analysis shows that a smaller value of the factor can be adopted.

TABLE 12.1

FACTORS TO ALLOW FOR

VARIABILITY OF STRUCTURAL UNITS

Number of similar

units to be tested

Strength

limit state

Serviceability

limit state

2 1.4 1.2

3 1.3 1.2

4 1.3 1.1

5 to 9 1.3 1.1

10 or more 1.2 1.1

12.3.4 Test procedure

The method of applying the test load to a prototype beam shall reflect the most adverse

conditions expected to apply during the in-service condition.

A prototype test shall be conducted according to the following procedure:

(a) Before applying any load, record the original position of the beam.

(b) Apply the test load for the relevant limit state as determined from Clause 12.1.3.


AS 2327.1—2003 80


(c) Maintain the test load for the necessary period.

(d) Remove the test load.

12.3.5 Criteria for acceptance

The group of beams represented by the prototypes shall be deemed to comply with the

requirements of this Standard for serviceability and strength if both of the following

requirements are satisfied:

(a) Acceptance for strength The test beam shall be deemed to comply with the

requirements for strength if it is able to sustain the strength limit state test load for at

least 5 minutes without incurring any significant damage.

(b) Acceptance for serviceability The maximum deflection of any beam under the

serviceability limit state test load shall be within the serviceability deflection limits

appropriate to the structure.

12.3.6 Acceptance of manufactured beams

Manufactured beams shall be similar in all respects to the beams tested.

12.4 TEST REPORTS

A report shall be prepared, which shall contain, in addition to the test load and deflection

records, a clear description of the test set-up, including the methods of supporting and

loading the members as appropriate, the method of measuring deflections and any other

relevant data. The report shall also contain a statement as to whether or not the structure,

substructure or members tested satisfied the relevant acceptance criteria in Clauses 12.2.2

or 12.3.6 as appropriate.


81 AS 2327.1—2003


APPENDIX A

LIST OF REFERENCED DOCUMENTS

(Normative)

The following documents are referred to in this Standard:

AS

1110 ISO metric hexagon precision bolts and screws (all parts)

1111 ISO metric hexagon commercial bolts and screws (all parts)

1112 ISO metric hexagon nuts, including thin nuts, slotted nuts and castle nuts (all

parts)

1163 Structural steel hollow sections

1170 Minimum design loads on structures

1170.4 Part 4: Earthquake loads

1275 Metric screw threads for fasteners

1379 Specification and supply of concrete

1397 Steel sheet and strip—Hot-dipped zinc-coated or aluminium/zinc-coated

1530 Methods for fire tests on building materials, components and structures

1530.4 Part 4: Fire-resistance test of elements of building construction

1554 Structural steel welding

1554.2 Part 2: Stud welding (steel studs to steel)

3600 Concrete structures

3610 Formwork for concrete

3610Supp 2 Formwork for concrete—Commentary

3784 Coatings for fire protection of building elements

3784.1 Part 1: Guide to selection and installation of sprayed mineral coatings

4100 Steel structures

AS/NZS

1170 Structural design actions

1170.0 Part 0: General principles

1170.1 Part 1: Permanent, imposed and other actions

1170.2 Part 2: Wind actions

1170.3 Part 3: Snow and ice actions

NOTE: At the time of publishing the Building Code of Australia (BCA) references the

AS 1170.3—1990 edition

1252 High-strength steel bolts with associated nuts and washers for structural

engineering

1365 Tolerances for flat-rolled steel products

1554 Structural steel welding

1554.1 Part 1: Welding of steel structures

1554.4 Part 4: Welding of high-strength quenched and tempered steels

1594 Hot-rolled steel flat products

3678 Structural steel—Hot-rolled plates, floorplates and slabs


AS 2327.1—2003 82


3679 Structural steel

3679.1 Part 1: Hot-rolled bars and sections

3679.2 Part 2: Welded I-sections

4671 Steel reinforcing materials

HB 77 Australian Bridge Design Code

BS

5950 Structural use of steelwork in building

5950-3 Part 3: Design in composite construction. Code of practice for design of

simple and continuous composite beams


83 AS 2327.1—2003


APPENDIX B

CALCULATION OF DEFLECTIONS BY SIMPLIFIED METHOD

(Normative)

B1 DESIGN PROCEDURE

Design for deflection in accordance with the simplified method defined in Clause 7.2.4

shall be performed as follows (see Figure B1):

(a) Determine which of the deflection components defined in Paragraph B2 are relevant

to the design, and calculate the corresponding serviceability design loads.

(b) Identify the different cross-sections along the steel beam during Construction

Stages 1 to 3, and along the composite beam during Construction Stages 5 and 6 and

the in-service condition. Calculate their elastic section properties, which in the case

of the composite beam shall initially be performed assuming full interaction in

accordance with Paragraph B3.

(c) Calculate the maximum stress (fmax) that occurs in the steel beam during Construction

Stages 1 to 6 and the in-service condition in accordance with Paragraph B4, and

check that it does not exceed 0.9 fyb in magnitude.

(d) Identify the maximum moment cross-section of the composite beam during the in-

service condition and calculate the degree of shear connection βm at this cross-section

in accordance with Section 6 (see Note 1).

(e) Calculate the effective second moment of areas Ieti and Ietl of the different composite

beam cross-sections identified in Step (b) accounting for the degree of shear

connection βm calculated at Step (d), in accordance with Paragraph B3.4.

(f) Calculate the magnitude of the relevant deflection components assuming linear-elastic

behaviour, accounting for changes in cross-section along the length of the beam and

the magnitude and distribution of applied loads.

(g) Calculate the corresponding values of the total and incremental deflections according

to the following equations as appropriate:

(i) Total deflection measured from slab top face:

IshIIiC5.6totδδδδδ +++=

l . . . B1(1)

(ii) Total deflection measured from steel beam soffit (see Note 2):

precamberIshIIiC5.6C1.3tot

−++++= δδδδδδl

. . . B1(2)

(iii) Incremental deflection calculated assuming formwork/falsework or props

removed before installation of brittle finishes (see Note 3):

IshIIiinc6.0 δδδδ ++=

l . . . B1(3)


AS 2327.1—2003 84


(h) Check that the limits chosen for the total and incremental deflections are not

exceeded.

NOTES:

1 If the maximum moment occurs at more than one cross-section, then the degree of shear

connection βm is calculated as the maximum degree of shear connection that occurs for

any of these cross-sections.

2 Advice on limits for cambering steel beams is given in Reference 8, Appendix I.

3 In the derivation of this equation it is assumed that 40% of the shrinkage deflection δIsh occurs before the attachment of brittle elements. A different allowance may be made by

adjusting the value of the coefficient of δIsh.


85 AS 2327.1—2003


FIGURE B1 FLOW CHART SHOWING SIMPLIFIED METHOD OF DEFLECTION DESIGN


AS 2327.1—2003 86


B2 DEFLECTION COMPONENTS AND CORRESPONDING DESIGN LOADS

Design loads shall be determined for the serviceability limit state. The loads may be

concentrated or distributed, acting directly on the steel or composite beam, or may be

concentrated loads on the steel beam resulting from attached members.

The components of deflection to be considered in the incremental and total deflection, and

the corresponding design loads, shall be determined from the following as appropriate:

(a) Immediate deflection of steel beam during Construction Stages 1 to 3 (δC1.3).

Deflections arising from the weight of the steel beam, formwork (permanent or

removable), concrete and reinforcement (i.e., dead loads GC1.3).

(b) Immediate deflection of composite beam during Construction Stages 5 and 6 (δC5.6).

Deflections arising from removal of formwork/falsework supporting dead loads

(GC1.3), and from the addition of any superimposed dead loads (Gsup) (see Note 1).

(c) Immediate deflection of composite beam during in-service condition (δIi). Deflection

arising from the short-term component of the live load (ψsQ).

(d) Long-term creep deflection of composite beam during in-service condition (δIl).

Creep deflections arising from the dead loads Gsup, and the long-term component of

the live load (ψlQ) (see Note 2) and, for propped construction only, GCl.3.

(e) Long-term shrinkage deflection of the composite beam during the in-service condition

(δIsh). Deflections arising from shrinkage of the concrete (see Note 3).

NOTES:

1 The resultant forces that act on the composite beam as a result of removing the falsework

or props are affected by the formwork/falsework or propping arrangement.

2 The long-term deflection calculated directly using the long-term section property includes

the contribution from the immediate deflection. Therefore, the component δIl has to be

calculated by subtracting the combined immediate deflection due to the loads Gsup and

ψlQ and, if propped, GC1.3 from the long-term deflection calculated using these same

loads.

3 An acceptable method for calculating the deflection is given in Reference 8, Appendix I.

B3 ELASTIC SECTION PROPERTIES OF COMPOSITE BEAM CROSS-

SECTIONS ASSUMING FULL INTERACTION

B3.1 General

The elastic section properties of a composite beam cross-section, assuming full interaction

between the steel beam and concrete slab (see Figure B3.1), shall be calculated taking into

account the position of the elastic neutral axis within the depth of the member in

accordance with Paragraphs B3.2 and B3.3, ignoring the tensile strength of the concrete.

The properties shall be calculated using the effective section determined in accordance with

Clause 5.2 assuming complete shear connection, i.e., β = 1. The modular ratio α shall be

taken as Es/Ec for the calculation of steel stresses or immediate deflection components using

Iti, and 3Es/Ec for the calculation of long-term deflection components using Itl, where the

modulus of elasticity of concrete Ec shall be determined in accordance with AS 3600 taking

into account the mean value of the compressive strength of the concrete at the relevant age.

The modulus of elasticity of the steel beam Es shall be taken as equal to 200 × 103

MPa. In

composite slabs, the width of concrete between the sheeting ribs measured perpendicular to

the longitudinal axis of the steel beam is calculated using the factor λ determined from

Clause 5.2.2.2.


87 AS 2327.1—2003


FIGURE B3.1 GEOMETRY OF COMPOSITE BEAM AS AN EQUIVALENT STEEL

SECTION FOR CALCULATION OF ELASTIC SECTION PROPERTIES

B3.2 Elastic neutral axis in concrete slab

When the elastic neutral axis is located in the concrete slab, calculations shall be as

follows:

(a) Solid slab (i.e., kDb ≤ Dc):

( )[ ]111

sg

b 42

cccd

kD ααα −+= . . . B3.2(1)

2

bsgss

3

bcft )(

3

)(kDdAI

kDbI −++=

α . . . B3.2(2)

where

kDb = depth of elastic neutral axis below top surface of slab

It = second moment of area of transformed section with respect to steel

c1 =

sgcf

s2

db

A

NOTE: Iti = It using α = Es/Ec and Itl = It using α = 3Es/Ec

(b) Composite slab with λ = 0:

(i) Neutral axis in cover slab (i.e., kDb ≤ (Dc − hr))

( )[ ]111

sg

b 42

cccd

kD ααα −+= . . . B3.2(3)

( ) ( )2bsgss

3

bcft

3kDdAI

kDbI −++=

α . . . B3.2(4)

(ii) Neutral axis in concrete between sheeting ribs (i.e. (Dc − hr) < kDb ≤ Dc)

( ) ( )

−

+−= + srccf

sgs

2

rccf

b /2AhD

bdAhD

bkD

αα . . . B3.2(5)


AS 2327.1—2003 88


( ) ( ) ( ) ( )2rcbrccf

3

rccf2

bsgsst 2412

hDkDhDbhDb

kDdAII +−−+−+−+=αα

. . . B3.2(6)

(c) Composite slab with λ > 0:

(i) Neutral axis in cover slab (i.e., kDb ≤ (Dc − hr))

( )[ ]111

sg

b 42

cccd

kD ααα −+= . . . B3.2(7)

( ) ( )2bsgss

3

bcft

3kDdAI

kDbI −++=

α

. . . B3.2(8)

(ii) Neutral axis in concrete between sheeting ribs (i.e., (Dc − hr) < kDb ≤ Dc)

−−

−+++

+= 21

5.0

sg

rc122

11sg

b

(224

2c

c

d

hDccc

ccdkD

λα

λα

λα

λα

..B3.2(9)

( ) ( ) ( )

( ) ( )2rcbrccf

3

rccf2

bsgss

3

rcbcft

24

123

hDkDhDb

hDbkDdAI

hDkDbI

+−

−+

−+−+++−=

α

ααλ

. . . B3.2(10)

where

( ) ( )rc

sg

2

12hD

dc −−=

λλ

B3.3 Elastic neutral axis in steel beam

When the elastic neutral axis is located in the steel beam (i.e., kDb > Dc), calculations shall

be as follows:

(a) Solid slab:

+

+= s

ccfsgs

2

ccfb /

2A

DbdA

DbkD

αα . . . B3.3(1)

( ) ( )2cbccf

3

ccf2

bsgsst 2412

DkDDbDb

kDdAII −++−+=αα

. . . B3.3(2)

(b) Composite slab with λ ≥ 0:

( ) ( ){ }

( )

++−

+++−=

srrccf

sgsrcr

2

rccf

b /22

AhhDb

dAhDhhDb

kD

λα

λα

. . . B3.3(3)

( ) ( ) ( ) ( )2

rcb

rcf

3

rcf

2

rcbrccf

3

rccf2

bsgsst

212

2412

+−++

+−−+−+−+=

hDkD

hbhb

hDkDhDbhDb

kDdAII

αλ

αλ

αα

. . . B3.3(4)


89 AS 2327.1—2003


B3.4 Effective second moments of area of composite beam

For composite beams with partial shear connection at the cross-section under maximum

bending (i.e., βm < 1), the effective second moments of area (Ieti and Ietl) shall be calculated

as follows:

Ieti = Iti + 0.6 (1 − βm) (Is − Iti) . . . B3.4(1)

Ietl = Itl + 0.6 (1 − βm) (Is − Itl) . . . B3.4(2)

where

Iti and Itl are calculated in accordance with Paragraph B3.1.

B4 MAXIMUM STRESS IN STEEL BEAM

The maximum tensile or compressive stress that occurs in the steel beam during

Construction Stages 1 to 6 and during the in-service condition, shall be calculated taking

into account the support conditions of the steel or composite beam, the magnitude and

distribution of the applied loads, and the stage at which composite action is developed.

Maximum stresses shall be calculated in accordance with the following:

(a) Construction Stages 1 to 3 Prior to the development of composite action, the

maximum stress in the steel beam shall be calculated using the load combination

G + Q considering Construction Stages 1 to 3 separately. The values of nominal dead

and live loads G and Q defined in Clause 4.2 appropriate to each construction stage

shall be used.

The section moduli of the steel beam Zst and Zsb corresponding to the extreme top and

bottom fibres of the steel beam shall be calculated as Is/ds and Is/(Ds − ds),

respectively, where ds is the depth of the elastic neutral axis of the steel beam below

the top of the beam.

(b) Construction Stages 5 to 6 Following the development of composite action, the

maximum stress in the steel beam shall be calculated taking into account the initial

stress in the beam locked in when the concrete sets, and the additional stress that

results when the composite beam is subsequently loaded, ignoring the effects of

concrete creep and shrinkage.

The section moduli of the composite beam Zct and Zcb corresponding to the extreme

top and bottom fibres of the steel beam shall be calculated, assuming full interaction,

as Iti/(Db − kDb − Ds) and Iti/(Db − kDb) respectively, where kDb and Iti are calculated

in accordance with Paragraph B3. At cross-sections where the steel stresses are being

calculated and β < 0.4, composite action shall be ignored and the section moduli of

the steel beam alone shall be used.

The stresses in the steel beam immediately prior to initial set of the concrete shall be

calculated assuming the beam supports the permanent dead load GC1.3 defined in

Paragraph B2. The load on the composite beam shall be calculated using the load

combination Gsup + Q, where Gsup equals the superimposed dead load applied during

Construction Stages 5 and 6, and Q equals the value of nominal live load defined in

Paragraph F2.6, Appendix F appropriate to each of these construction stages.

(c) In-service condition During the in-service condition, the additional stresses that

arise from live load Q acting on the composite beam shall be calculated using ψsQ.

The section moduli of the composite beam Zct and Zcb corresponding to the extreme

top and bottom fibres of the steel beam shall be calculated, assuming full interaction,

as Iti(Db − kDb − Ds) and Iti/(Db − kDb) respectively, where kDb and Iti shall be

calculated in accordance with Paragraph B3. At cross-sections where the steel stresses

are being calculated and β < 0.4, composite action shall be ignored and the section

moduli of the steel beam alone shall be used.


AS 2327.1—2003 90


APPENDIX C

SUGGESTED LIMITS FOR CALCULATED DEFLECTIONS

(Informative)

C1 BEAMS

The deflection limit chosen should not exceed the relevant value given in Table C1 unless it

can be shown that exceeding these values will not impair the serviceability of the member.

TABLE C1

SUGGESTED LIMITS FOR CALCULATED DEFLECTION OF BEAMS

Type of member Deflection to be

considered

Deflection limitation

(∆∆∆∆/Lef) for span (see

Note 1)

Deflection limitation

(∆∆∆∆/Lef) for cantilevers

(see Note 2)

All members The total deflection 1/250 1/125

Members

supporting brittle

elements

The incremental

deflection that occurs after

the addition or attachment

of the elements

1/500 where provision

is made to minimize the

effect of movement,

otherwise 1/1000

1/250 where provision is

made to minimize the

effect of movement,

otherwise 1/500

NOTES:

1 Deflection limits given may not safeguard against ponding of water.

2 For cantilevers, the values of ∆/Lef given in this Table apply only if the rotation at the support is

included in the calculation of ∆.

C2 PROFILED STEEL SHEETING

The vertical deflection of the sheeting under its own weight plus the weight of plastic

concrete and reinforcement, but excluding the construction loads, should not exceed the

lesser of 30 mm or—

(a) Lef/240 where visual quality and general alignment of the slab soffit is considered

important, or the deflection of the soffit affects the application of finishes or the

installation of building services; or

(b) Lef/130 in other cases,

where Lef is the effective span between supports (props being supports in this context), which

can be calculated from Figure H1(a) by substituting hr for Ds, irrespective of whether or not

the sheeting is continuous past the support.


91 AS 2327.1—2003


APPENDIX D

CALCULATION OF DESIGN MOMENT CAPACITY (φMbv) AS A FUNCTION OF DEGREE OF SHEAR CONNECTION (β)

(Normative)

D1 GENERAL

In accordance with Clause 6.4, the design moment capacity (φMbv) shall be calculated as a

function of the degree of shear connection β from—

(a) Paragraph D2 if γ ≤ 0.5; or

(b) Paragraph D3 if 0.5 < γ ≤ 1.

NOTE: The steel section has been modelled on a mono-symmetric I-section. For other types of

steel sections, the same equations can be used noting that—

(a) for sections with multiple webs, the I-section web thickness should be taken as the sum of

the effective thicknesses of the webs; and

(b) for sections without a bottom flange, the bottom flange area (Af2) should be taken as zero.

D2 CROSS-SECTIONS WHERE γγγγ ≤≤≤≤ 0.5

D2.1 General

At beam cross-sections where γ ≤ 0.5, the design moment capacity φMbv shall be assumed to

be independent of the shear ratio γ and in this case equals φMb.

D2.2 Calculation of φφφφMb as a function of ββββ

The design moment capacity φMb may be calculated as a continuous function of β as shown

in Figure D2.2(a) by using the equations based on rectangular stress block theory given in

Paragraph D2.3.

Alternatively, a bilinear approximation to the continuous function shown in Figure D2.2(a)

may be used to calculate the relationship between φMb and β. This requires the design

moment capacities φMs, φMbc and φMb.5 (i.e., φMb when β = 0.5) to be calculated from

Paragraph D2.3. Linear interpolation shall be used to calculate φMb between these points as

follows (see Figure D2.2(b)):

(a) 0 < β ≤ 0.5

bMφ =

b.5s2)21( MM βφφβ +− . . . D2.2(1)

(b) 0.5 < β < 1.0

bMφ =

b.5bc)1(2)12( MM φβφβ −−− . . . D2.2(2)

D2.3 Nominal moment capacities Mbc and Mb for γγγγ ≤≤≤≤ 0.5

D2.3.1 General

At beam cross-sections where γ ≤ 0.5—

(a) the nominal moment capacity Mbc corresponding to complete shear connection,

(i.e., β = 1.0) shall be determined in accordance with Paragraph D2.3.2; and


AS 2327.1—2003 92


(b) the nominal moment capacity Mb corresponding to partial shear connection,

(i.e., β < 1.0) shall be determined in accordance with Paragraph D2.3.3.

NOTE: The equations for Mbc and Mb given in Paragraphs D2.3.2 and D2.3.3 have been derived

using rectangular stress block theory based on the following assumptions and calculation

principles:

(a) In accordance with Section 5, the effective section of the composite beam cross-section

comprises an effective width of the concrete compression flange bcf (which takes account of

the effects of in-plane shear flexibility, i.e., shear-lag) and an effective portion of the steel

beam (such that all its compression plate elements are compact).

(b) The concrete has zero tensile strength.

(c) The presence of any longitudinal reinforcement in the slab is ignored.

FIGURE D2.2 DESIGN MOMENT CAPACITY φMb AS A FUNCTION OF β WHEN γ ≤ 0.5


93 AS 2327.1—2003


(d) Any profiled steel sheeting does not support either longitudinal tensile or compressive forces

in the spanning direction of the beam.

(e) A uniform compressive stress of 0.85f′ c develops in the concrete over the slab effective width

directly below the top surface of the slab.

(f) The orientation of the sheeting ribs with respect to the longitudinal axis of the steel beam

affects the transfer of longitudinal compressive forces in the concrete between the sheeting

ribs (see Paragraph D2.3.2).

(g) The compressive force in the concrete cannot exceed the longitudinal shear force, which can

be transferred by the shear connection between the steel beam and the concrete slab at the

strength limit state.

(h) The part of the effective portion of the steel beam in tension is stressed uniformly to the yield

stress of either the flanges (fyf) or webs (fyw) as appropriate.

(i) Any part of the steel beam in compression is stressed uniformly to the yield stress of either the

flanges (fyf) or webs (fyw) as appropriate, and the strain gradient across the plastic neutral axis

is infinite, i.e., strain-compatibility is ignored.

(j) The resultant tensile force in the steel beam equals the compressive force in the concrete slab

and, therefore, the force in the concrete cannot exceed the tensile capacity of the steel beam.

D2.3.2 Nominal moment capacity Mbc (β = 1.0)

The nominal moment capacity at a cross-section of a composite beam with complete shear

connection (Mbc) shall be determined in accordance with the procedure below, referring to

Figure D2.3.2 for notation. It should be noted that the equations for the unusual case when

the compressive stress zone falls within the bottom flange of the steel beam have not been

formulated.

(a) Calculate—

(i) Fst = (Af1 + Af2) fyf + Aw fyw; and . . . D2.3.2(1)

(ii) dsr

where

Fst = tensile force in steel beam, assuming that the entire cross-sectional area

is yielded in tension

dsr = depth at which Fst acts below the top surface of the slab, noting that dsr

equals dsg unless the section is monosymmetric and fyf does not equal

fyw

(b) Calculate the following compressive forces:

c1F = )(85.0rccfchDbf −′ . . . D2.3.2(2)

c2F = rcfc

85.0 hbf λ′ . . . D2.3.2(3)

scfF = fl1sfyf tbf . . . D2.3.2(4)

where

Fc1 = longitudinal compressive capacity of concrete cover slab within slab

effective width

Fc2 = longitudinal compressive capacity of concrete between steel ribs

within slab effective width

Fscf = compressive capacity of top flange of steel beam

λ = as defined in Clause 5.2.2.2

NOTES:

1 hr = 0 for solid slabs.

2 Fc2 = 0 if steel sheeting ribs are perpendicular to steel beam, i.e., θ = 90°.


AS 2327.1—2003 94


FIGURE D2.3.2 NOTATION FOR Mbc DETERMINATION


95 AS 2327.1—2003


(c) Calculate dc, dh, Fcc and finally Mbc from the appropriate case of those that follow

defined by the bounds on Fst:

(i) Case 1 Fst ≤ Fc1

If Fst ≤ Fc1, then dh ≤ (Dc − hr); and

dc = dh = (Dc − hr) Fcc/Fc1 . . . D2.3.2(5)

Fcc = Fst

Mbc = Fcc (dsr − dc/2) . . . D2.3.2(6)

(ii) Case 2 Fc1 < Fst ≤ (Fc1 + Fc2)

If Fc1 < Fst ≤ (Fc1 + Fc2), then (Dc − hr) < dh ≤ Dc; and

dc = dh = (Dc − hr) + [hr(Fst − Fc1)/Fc2] . . . D2.3.2(7)

Fcc = Fst

Mbc = Fc1[dsr − (Dc − hr)/2]+(Fcc − Fc1)[dsr − dh/2 − (Dc − hr)/2] . . . D2.3.2(8)

(iii) Case 3 (Fc1 + Fc2) < Fst ≤ (Fc1 + Fc2 + 2Fscf)

If (Fc1 + Fc2) < Fst ≤ (Fc1 + Fc2 + 2Fscf), then Dc < dh ≤ (Dc + tf1); and

dc = Dc

Fcc = Fc1 + Fc2; Fsc = Fst − Fcc . . . D2.3.2(9)

dh = Dc + tf1Fsc/(2Fscf) . . . D2.3.2(10)

Mbc = Fc1 [ds − (Dc − hr)/2] + Fc2 (dsr − Dc + hr/2)

+ Fsc [dsr − (Dc + dh)/2] . . . D2.3.2(11)

(iv) Case 4 (Fc1 + Fc2 + 2Fscf) < Fst

If (Fc1 + Fc2 + 2Fscf) < Fst, then (Dc + tf1) < dh ≤ dsr; and

dc = Dc

Fcc = Fc1 + Fc2

Calculate compressive force component in steel beam web(s) Fb:

Fb = Fst − Fcc − 2Fscf . . . D2.3.2(12)

dh = Dc + tf1 + Fb/(2fywtw) . . . D2.3.2(13)

Mbc = Fc1 [dsr − (Dc − hr)/2] + Fc2(dsr − Dc + hr/2)

+ 2Fscf (dsr − Dc − tf1/2) + Fb[dsr − (Dc + tf1 + dh)/2] . . . D2.3.2(14)

D2.4 Nominal moment capacity Mb (0 < ββββ < 1.0)

The nominal moment capacity of a cross-section of a composite beam with partial shear

connection (Mb) shall be determined in accordance with the following procedure, referring to

Figure D2.3.3 for notation:

(a) Calculate Fst and dsr from Paragraph D2.3.2(a).

(b) Calculate Fc1, Fc2 and Fscf from Paragraph D2.3.2(b).

(c) Calculate Fcc from Paragraph D2.3.2(c) for the applicable case corresponding to

complete shear connection.

(d) Calculate Fcp from either—

(i) when the strength of the shear connection is known—

Fcp = ni fds . . . D2.3.3(1)

< Fcc (otherwise the cross-section has complete shear connection); or


AS 2327.1—2003 96


(ii) when the degree of shear connection β (< 1.0) is specified—

Fcp = βFcc . . . D2.3.3(2)

(e) Calculate—

Fsc = Fst − Fcp . . . D2.3.3(3)

(f) Calculate dc from one of the following as appropriate:

(i) If Fcp ≤ Fc1, then dc ≤ (Dc − hr); and

dc = (Dc − hr) Fcp/Fc1 . . . D2.3.3(4)

(ii) If Fcp > Fc1, then (Dc − hr) < dc ≤ Dc; and

dc = Dc − hr + hr (Fcp − Fc1)/Fc2 . . . D2.3.3(5)

(g) Calculate dh from one of the following as appropriate:

(i) If Fsc ≤ 2Fscf, then Dc < dh ≤ (Dc + tf1); and

dh = Dc + tf1 Fsc/(2Fscf) . . . D2.3.3(6)

(ii) If 2Fscf < Fsc ≤ 2Fscf + 2Fscw, then (Dc + tf1) < dh ≤ (Dc + Ds − tf2); and

dh = Dc + tf1 + (Fsc − 2Fscf)/(2 fyw tw) . . . D2.3.3(7)

where

Fscw = fyw d1 tw

(iii) If Fsc > 2Fscf + 2Fscw, then (Dc + Ds − tf2) < dh ≤ (Dc + Ds), and

dh = Dc + Ds − tf2 + (Fsc − 2Fscf − 2Fscw)/(2 fyf bsf2) . . . D2.3.3(8)

(h) Calculate Mb from the appropriate case following defined by the bounds on Fcp and Fsc,

using the relevant values of dc and dh from (f) and (g), respectively:

(i) Case 1 Fcp ≤ Fc1 and Fsc ≤ 2Fscf

If Fcp ≤ Fc1 and Fsc ≤ 2Fscf, then

Mb = Fcp (dsr − dc/2) + Fsc [dsr − (Dc + dh)/2] . . . D2.3.3(9)

where

dc is obtained from Equation D2.3.3(4); and

dh is obtained from Equation D2.3.3(6)

(ii) Case 2 Fcp ≤ Fc1 and 2Fscf < Fsc ≤ (2Fscf + 2Fscw)

If Fcp ≤ Fc1 and 2Fscf < Fsc ≤ (2Fscf + 2Fscw), then

Mb = Fcp (dsr − dc/2) + 2Fscf (dsr − Dc − tf1/2)

+ (Fsc − 2Fscf)[dsr − (Dc + tf1 + dh)/2] . . . D2.3.3(10)

where

dc is obtained from Equation 2.3.3(4); and

dh is obtained from Equation 2.3.3(7).


97 AS 2327.1—2003


FIGURE D2.3.3 (in part) NOTATION FOR Mb DETERMINATION


AS 2327.1—2003 98


(iii) Case 3 Fcp ≤ Fc1 and Fsc > (2Fscf + 2Fscw)

If Fcp ≤ Fc1 and Fsc > (2Fscf + 2Fscw), then

Mb = Fcp (dsr − dc/2) + 2Fscf (dsr − Dc − tf1/2)

+ 2Fscw [dsr − Dc − (Ds + tf1 − tf2)/2]

+ Fb [dsr − (Dc + Ds − tf2 + dh)/2]

. . . D2.3.3(11)

where

dc is obtained from Equation D2.3.3(4);

dh is obtained from Equation D2.3.3(8); and

Fb = Fsc − 2Fscf − 2Fscw

(iv) Case 4 Fcp > Fc1 and Fsc ≤ 2Fscf

If Fcp > Fc1 and Fsc ≤ 2Fscf, then

Mb = Fc1 [dsr − (Dc − hr)/2] + (Fcp − Fc1)[dsr −(Dc − hr + dc)/2]

+ Fsc [dsr − (Dc + dh)/2]

. . . D2.3.3(12)

where


dh is obtained from Equation D2.3.3(6).

(v) Case 5 Fcp > Fc1 and 2Fscf < Fsc ≤ (2Fscf + 2Fscw)

If Fcp > Fc1 and 2Fscf < Fsc ≤ (2Fscf + 2Fscw), then

Mb = Fc1[dsr − (Dc − hr)/2] + (Fcp − Fc1)[dsr − (Dc − hr + dc)/2]

+ 2Fscf(dsr − Dc − tf1/2) + (Fsc − 2Fscf)[dsr − (Dc + tf1 + dh)/2]

. . . D2.3.3(13)

where



(vi) Case 6 Fcp > Fc1 and Fsc > (2Fscf + 2Fscw)

If Fcp > Fc1 and Fsc > (2Fscf + 2Fscw), then

Mb = Fc1 [dsr − (Dc − hr)/2] + (Fcp − Fcl) [dsr − (Dc − hr + dc)/2]

+ 2Fscf (dsr − Dc − tf1/2) + 2Fscw[dsr − Dc − (Ds + tf1 − tf2)/2]

+ Fb [dsr − (Dc + Ds − tf2 + dh)/2] . . . D2.3.3(14)

where



Fb = Fsc − 2Fscf − 2Fscw


99 AS 2327.1—2003


FIGURE D2.3.3 (in part) NOTATION FOR Mb DETERMINATION


AS 2327.1—2003 100


D3 CROSS-SECTIONS WHERE 0.5 < γγγγ ≤≤≤≤ 1

D3.1 General

At beam cross-sections where 0.5 < γ ≤ 1.0, the design moment capacity φMbv shall be

assumed to be dependent on the shear ratio γ according to the appropriate relationship

defined in Paragraph D3.2, as well as the degree of shear connection β.

D3.2 Relationship with γγγγ

For a particular value of β < 1.0, it shall be assumed that φMbv reduces linearly from φMb

when γ = 0.5 to φMbf when γ = 1.0 (i.e., φMbf is the design moment capacity with the concrete

slab and steel beam flanges only, and both φMb and φMbf shall be calculated in accordance

with Paragraph D3.3) (see Figure D3.2), i.e.

φMbv = φMb − (φMb − φMbf) (2γ − 1) . . . D3.2(1)

Similarly, for β = 1.0 it shall be assumed that φMbv reduces linearly from φMbc when γ = 0.5

to φMbfc when γ = 1.0, where Mbc and Mbfc shall be calculated in accordance with

Paragraphs D2.3.2 and D3.4.2 respectively (see Figure D3.2), i.e.

φMbv = φMbc − (φMbc − φMbfc) (2γ − 1) . . . D3.3(2)

FIGURE D3.2 RELATIONSHIP BETWEEN φMbv AND γ FOR 0 ≤ β ≤ 1.0

D3.3 Calculation of φφφφMb and φφφφMbf as a function of ββββ

The values of φMb and φMbf for use in Equation D3.2(1) shall be calculated from one of the

following:

(a) φMb and φMbf as continuous functions of β (see Figure D3.3(a)) Calculate the nominal

moment capacity Mb in accordance with Paragraph D2.3.3 and the nominal moment

capacity Mbf shall be calculated in accordance with Paragraph D3.4.3.

(b) φMb and φMbf as approximate bi-linear functions of β (see Figure D3.3(b)) First,

using the following equation, calculate the degree of shear connection (ψ) of the

composite beam with the whole of the effective portion of the steel beam included,

corresponding to when the section with the flanges only (i.e., web ignored) has

complete shear connection:

ψ = Fccf /Fcc . . . D3.3(1)


101 AS 2327.1—2003


where

Fccf = compressive force in the concrete slab corresponding to complete shear

connection (β = 1.0) when the web of the steel beam is ignored (i.e.,

γ = 1.0), calculated using Paragraph D3.4.2

Fcc = compressive force in the concrete slab corresponding to complete shear

connection (β = 1.0) when the whole of the effective portion of the steel

beam is included (i.e., γ ≤ 0.5), calculated using Paragraph D2.3.2

Second, calculate φMb and φMbf from either of the following pairs of equations

depending on the magnitude of β with respect to ψ:

(i) For 0 < β ≤ ψ

φMb = [φMs (ψ − β) + φMb.ψ β] / ψ . . . D3.3(2)

φMbf = [φMs (ψ − β) + φMbfc β] / ψ . . . D3.3(3)

FIGURE D3.3 DESIGN MOMENT CAPACITY φMbv AS A FUNCTION OF β WHEN γ > 0.5


AS 2327.1—2003 102


(ii) For ψ < β < 1.0

φMb = [φMb.ψ (1 − β) + φMbc (β − ψ)]/(1 − ψ) . . . D3.3(4)

φMbf = φMbfc . . . D3.3(5)

where φMb.ψ is the value of φMb when γ ≤ 0.5 and β = ψ, and Mb shall be

calculated using Paragraph D2.3.3.

D3.4 Nominal moment capacities Mbfc and Mbf for γγγγ = 1.0

D3.4.1 General

When γ = 1.0, the web of the steel beam shall be ignored and the nominal moment capacities

of the composite beam Mbfc and Mbf determined in accordance with—

(a) Paragraph D3.4.2 for complete shear connection (ψ ≤ β ≤ 1.0); and

(b) Paragraph D3.4.3 for partial shear connection (β < ψ).

D3.4.2 Nominal moment capacity Mbfc (ψ ≤ β ≤ 1.0)

The nominal moment capacity Mbfc shall be determined in accordance with the following

procedure, referring to Figure D3.4.2 for notation:

(a) Calculate the following:

(i) Fstf = (Af1 + Af2) fyf . . . D3.4.2(1)

(ii) dsr

where

Fstf = tensile capacity of the steel beam flanges

dsr = depth at which Fstf acts below the top surface of the slab

(b) Calculate the following compressive forces:

(i) Fc1 from Equation D2.3.2(2).

(ii) Fc2 from Equation D2.3.2(3).

(iii) Fscf from Equation D2.3.2(4).

(c) Calculate dc, dh, Fccf and finally Mbfc from the following appropriate cases defined by

the bounds on Fstf:

(i) Case 1 Fstf ≤ Fc1

If Fstf ≤ Fc1, then dh ≤ (Dc − hr); and

dc = dh = (Dc − hr)Fccf/Fc1 . . . D3.4.2(2)

Fccf = Fstf

Mbfc = Fccf (dsr − dc/2) . . . D3.4.2(3)

(ii) Case 2 Fc1 < Fstf ≤ (Fc1 + Fc2)

If Fc1 < Fstf ≤ (Fc1 + Fc2), then (Dc − hr) < dh ≤ Dc; and

dc = dh = (Dc − hr) + hr(Fstf − Fc1)/Fc2 . . . D3.4.2(4)

Fccf = Fstf

Mbfc = Fc1[dsr − (Dc − hr)/2] + (Fccf − Fc1) [dsr − (Dc − hr + dh)/2]

. . . D3.4.2(5)


103 AS 2327.1—2003


(iii) Case 3 (Fc1 + Fc2) < Fstf < (Fc1 + Fc2 + 2Fscf)

If (Fc1 + Fc2) < Fstf < (Fc1 + Fc2 + 2Fscf), then Dc < dh ≤ (Dc + tf1); and

dc = Dc

Fccf = Fc1 + Fc2; Fsc = Fstf − Fccf . . . D3.4.2(6)

dh = Dc + tf1Fsc/(2Fscf) . . . D3.4.2(7)

Mbfc = Fc1[dsr − (Dc − hr)/2] + Fc2[dsr − Dc + hr/2]

+ Fsc[dsr − (Dc + dh)/2]

. . . D3.4.2(8)

NOTE: The equations for the unusual case when the compressive stress zone falls within the

bottom flange of the steel beam have not been formulated.

FIGURE D3.4.2 NOTATION FOR Mbfc DETERMINATION (γ = 1.0, β = 1.0)


AS 2327.1—2003 104


D3.4.3 Nominal moment capacity Mbf (0 < β < ψ)

The nominal moment capacity Mbf shall be determined in accordance with the following

procedure, referring to Figure D3.4.3 for notation:

(a) Calculate Fstf and dsr from Paragraph D3.4.2(a).

(b) Calculate Fc1, Fc2 and Fscf from Paragraph D3.4.2(b).

(c) Calculate Fccf from Paragraph D3.4.2(c) for the applicable case corresponding to

complete shear connection.

(d) Calculate Fcpf from either—

(i) when the strength of the shear connection is known—

Fcpf = nifds < Fccf; or . . . D3.4.3(1)

(ii) when the degree of shear connection β is specified—

Fcpf = βFcc < Fccf . . .D3.4.3(2)

(e) Calculate—

Fsc = Fstf − Fcpf . . . D3.4.3(3)

(f) Calculate dc from one of the following as appropriate:

(i) If Fcpf ≤ Fc1, then dc ≤ (Dc − hr); and

dc = (Dc − hr)Fcpf/Fc1 . . . D3.4.3(4)

(ii) If Fcpf > Fc1, then (Dc − hr) < dc ≤ Dc, and

dc = (Dc − hr) + hr (Fcpf − Fc1)/Fc2 . . . D3.4.3(5)

(g) Calculate dh from the following:

(i) If Fsc ≤ 2Fscf, then Dc < dh ≤ (Dc + tf1); and

dh = Dc + tf1 Fsc/(2Fscf) . . . D3.4.3(6)

(ii) If Fsc > 2Fscf, then (Dc + Ds − tf2) < dh ≤ (Dc + Ds); and

dh = Dc + Ds − tf2 + (Fsc − 2Fscf)/(2fyfbsf2) . . . D3.4.3(7)

(h) Calculate Mbf from the appropriate case following, defined by the bounds on Fcpf and

Fscf, using the relevant values of dc and dh from Steps (f) and (g) respectively:

(i) Case 1 Fcpf ≤ Fc1 and Fsc ≤ 2Fscf

If Fcpf ≤ Fc1 and Fsc ≤ 2Fscf, then

Mbf = Fcpf (dsr − dc/2) + Fsc[dsr − (Dc + dh)/2] . . . D3.4.3(8)

where



(ii) Case 2 Fcpf ≤ Fc1 and Fsc > 2Fscf

If Fcpf ≤ Fc1 and Fsc > 2Fscf, then

Mbf = Fcpf (dsr − dc/2) + 2Fscf[dsr − Dc − tf1/2]

+ Fb[dsr − (Dc + Ds − tf2 + dh)/2]

. . . D3.4.3(9)

where



Fb = Fsc − 2Fscf


105 AS 2327.1—2003


(iii) Case 3 Fcpf > Fc1 and Fsc ≤ 2Fscf

If Fcpf > Fc1 and Fsc ≤ 2Fscf, then

Mbf = Fc1[dsr − (Dc − hr)/2] + (Fcpf − Fc1)[dsr − (Dc − hr + dc)/2]

+ Fsc [dsr − (Dc +dh)/2] . . . D3.4.3(10)

where



(iv) Case 4 Fcpf > Fc1 and Fsc > 2Fscf

If Fcpf > Fc1 and Fsc > 2Fscf, then

Mbf = Fc1[dsr − (Dc − hr)/2] + (Fcpf − Fc1)[dsr − (Dc − hr + dc)/2]+

2Fscf [dsr − (Dc + tf1/2)] + Fb [dsr − (Dc + Ds − tf2 + dh)/2] . . . D3.4.3(11)

where



Fb = Fsc − 2Fscf


AS 2327.1—2003 106


FIGURE D3.4.3 NOTATION FOR Mbf DETERMINATION (γ = 1.0, 0.0 < β <1.0)


107 AS 2327.1—2003


APPENDIX E

FLOW CHARTS

(Informative)

E1 OVERALL DESIGN

Figure E1 shows the overall design process in the form of a flow chart. The shaded boxes

indicate the relevant Section of the Standard in which the particular requirements are located.

The horizontal dashed lines indicate the limits of the design procedures of the Standard

(except for Section 4), and dotted flows outside these limits refer to design in accordance

with the other Standards noted.

E2 CALCULATION OF EFFECTIVE CROSS-SECTION

The procedure to be followed when calculating the effective section of a composite beam

cross-section is shown diagrammatically in Figure E2 and is affected by the degree of shear

connection β of the beam cross-section. The procedure would be carried out for each

different potentially critical cross-section.

NOTE: When an initial assessment is made to determine the effective section of a composite beam

cross-section, the degree of shear connection β may not be known, in which case it is conservative

to ignore composite action and to calculate the depth of the compressive stress zone assuming only

the steel beam is present. In critical cases it will be beneficial to redetermine the effective section

once β is known more accurately.

E3 GENERAL PROCEDURE FOR STRENGTH DESIGN

The procedure to be followed for strength design is shown in Figure E3 in the form of a

flowchart. The shaded boxes indicate the Clause or Section of the Standard relevant to the

particular activity in the procedure.


AS 2327.1—2003 108


FIGURE E1 (in part) FLOW CHART OF OVERALL DESIGN PROCESS


109 AS 2327.1—2003


FIGURE E1 (in part) FLOW CHART OF OVERALL DESIGN PROCESS


AS 2327.1—2003 110


FIGURE E2 FLOW CHART SHOWING PROCEDURE FOR CALCULATING THE

EFFECTIVE SECTION OF A COMPOSITE BEAM CROSS-SECTION


111 AS 2327.1—2003


FIGURE E3 (in part) FLOW CHART SHOWING GENERAL

PROCEDURE FOR STRENGTH DESIGN


AS 2327.1—2003 112


FIGURE E3 (in part) FLOW CHART SHOWING GENERAL

PROCEDURE FOR STRENGTH DESIGN


113 AS 2327.1—2003


E4 PROCEDURE FOR DESIGN OF LONGITUDINAL SHEAR REINFORCEMENT

FOR TYPE 1, 2 AND 3 SHEAR SURFACES

The procedure to be followed for the design of longitudinal shear reinforcement for Type 1, 2

and 3 shear surfaces, is shown in Figure E4 in the form of a flowchart. The shaded boxes

indicate the Clause of the Standard relevant to the particular activity in the procedure.

FIGURE E4 FLOW CHART SHOWING PROCEDURE FOR DESIGN OF LONGITUDINAL SHEAR REINFORCEMENT (TYPES 1, 2 AND 3)


AS 2327.1—2003 114


APPENDIX F

CONSTRUCTION STAGES AND MINIMUM CONSTRUCTION LOADS

(Normative)

F1 CONSTRUCTION STAGES

The construction stages used for the purposes of assessing construction loads and the

initiation and development of composite action shall be as defined in Clause 4.2 and shown

diagrammatically in Figure F1(A) and pictorially in Figure Fl(B). The nominal minimum

construction loads associated with each stage shall be determined in accordance with

Paragraph F2.

FIGURE F1(A) CONSTRUCTION STAGES 1 TO 6


115 AS 2327.1—2003


Construction Stage 1 Construction Stage 1 (continued)

Construction Stage 2 Construction Stage 3

Construction Stages 5 and 6 Construction Stages 5 and 6 (continued)

FIGURE F1(B) ILLUSTRATIONS OF CONSTRUCTION STAGES 1 TO 6


AS 2327.1—2003 116


F2 MINIMUM NOMINAL LOADS FOR CONSTRUCTION

F2.1 General

The nominal construction loads specified in the Paragraphs below are the minimum values to

be used in assessing the structural adequacy of the profiled steel sheeting and the steel beam

during Construction Stages 1 to 4, and for the design of the composite beam during

Construction Stages 5 and 6. When formwork other than profiled steel sheeting is used,

construction loads shall be determined in accordance with AS 3610. Loads of variable

position shall be placed to cause the most adverse effect on the member.

F2.2 Construction Stage 1

F2.2.1 Profiled steel sheeting

During Construction Stage 1, the minimum nominal loads assumed to act on the profiled steel

sheeting shall be taken as follows:

(a) Dead load of steel sheeting.

(b) Live loads consisting of—

(i) a uniformly distributed load of 1.0 kN/m2; or

(ii) a concentrated load of 1.0 kN applied in the edge pan or 2.0 kN elsewhere,

concentrated on an area of 0.1 m × 0.1 m.

F2.2.2 Steel beam

During Construction Stage 1, the minimum nominal loads assumed to act either directly or

indirectly on the steel beam shall be taken as follows:

(a) Dead loads, consisting of the weight of the steel beam plus any formwork supported by

the beam.


(i) a concentrated load of 10.0 kN applied to the top flange of the steel beam

anywhere within the span; or

(ii) a uniformly distributed load acting on the formwork supported by the beam,

taken as—

(A) 0.5 kN/m2 if the tributary area A is less than or equal to 23 m

2;

(B) 0.3 kN/m2 if the tributary area A is greater than or equal to 46 m

2; or

(C) varying linearly between 0.5 and 0.3 kN/m2 if the tributary area A is

between 23 and 46 m2.

NOTE: The tributary area A is the sum of all areas of formwork supported by the steel

beam. When the formwork comprises profiled steel sheeting, the tributary area should be

calculated assuming one-way action of the sheeting.





(a) Dead loads, consisting of the weight of—

(i) the steel sheeting; and

(ii) the slab reinforcement placed on the sheeting.

NOTE: A typical allowance for slab reinforcement is 0.1 kN/m2 per 100 mm of overall

depth.


117 AS 2327.1—2003



(i) a uniformly distributed load of 5.0 kN/m2 (which includes an allowance for

stacked materials of 4.0 kN/m2); or

(ii) a concentrated load of 1.0 kN applied in the edge pan or 2.0 kN elsewhere,

concentrated on an area of 0.1 m × 0.1 m.

F2.3.2 Steel beam


indirectly on the steel beam shall be the same as those for Construction Stage 1.





(a) Dead loads as for Stage 2, plus—

(i) the weight of fresh concrete (see Note 1); and

(ii) the additional weight of fresh concrete due to ponding (see Note 2).

NOTES:

1 The density of normal-weight concrete may vary from 2100 kg/m3 to 2800 kg/m3 depending

on geographical location (see AS 3600).

2 The additional weight due to ponding of the concrete on the sheeting may be calculated by

assuming an average increase in slab depth equal to 0.7 times the maximum deflection of

the sheeting. However, if the steel beams supporting the sheeting also deflect appreciably,

then the effect of this movement should also be considered in the calculation.


(i) a uniformly distributed load of 1.0 kN/m2; or

(ii) a load of 2.0 kN/m2, distributed over an area of 1.6 m × 1.6 m anywhere within

the span, for localized mounding during concrete placement.

F2.4.2 Steel beam


indirectly on the steel beam shall be taken as follows:

(a) Dead loads as for the steel beam during Stage 2, plus—

(i) the weight of fresh concrete on the tributary area A; and

(ii) the additional weight of fresh concrete due to ponding.

NOTE: The combined deflections of the steel beams and the formwork as they affect the

overall magnitude of ponding need to be considered.

(b) Live loads, consisting of a uniformly distributed load acting on the formwork, taken

as—

(i) 1.0 kN/m2 if the tributary area A is less than or equal to 23 m

2;

(ii) 0.6 kN/m2 if the tributary area A is greater than or equal to 46 m

2; or

(iii) varying linearly between 1.0 and 0.6 kN/m2 if the tributary area A is between 23

and 46 m2.


AS 2327.1—2003 118



During Construction Stage 4, potential damage to the shear connection shall be avoided.

NOTE: Damage to the shear connection can be avoided by preventing either the imposition of

significant live loads on the slab, or the removal of any falsework or props supporting the slab or

the steel beam; or alternatively by back-propping the slab, or the steel beam or both (see also

Clause 11.4).

F2.6 Construction Stages 5 and 6

During Construction Stages 5 and 6, the minimum nominal loads assumed to act on the

composite beam shall include all of the following:

(a) Dead loads consisting of the weight of—

(i) the steel beam plus any applied finishes;

(ii) the concrete slab plus any applied finishes; and

(iii) any other items of permanent construction (e.g., suspended ceilings, permanent

partitions, reticulated services).

(b) Live loads, consisting of uniformly distributed loads placed over the tributary area of

the concrete slab (see Note 1), of magnitude—

(i) 1.0 kN/m2 if no levels above are directly supported by the beam (see Note 2); or

(ii) if the beam provides direct support to levels of construction above, 1.0 kN/m2 on

the topmost level and 0.25 kN/m2 on each level providing support to the next

level above.

(c) Unless otherwise provided in the project drawings or specification, a live-load

allowance for stacked materials of 4.0 kN/m2 distributed over an area of 2.5 m by

2.5 m, and located anywhere within the span.

NOTES:

1 The tributary area of the concrete slab is determined taking into account the presence of any

props supporting the slab and whether the slab exhibits either one-way or two-way action (see

Clause 5.3.5). Imposed load reduction may be applied in accordance with AS/NZS 1170.1.

2 In multistorey construction, where the floor structures of a number of lower levels are used to

provide support for the construction of each new level, the loads carried by the lowest

supporting floor during this period may well exceed the design loads for the strength

limit-state, and this loading case needs to be checked separately. Methods for determining these

loads, which depend primarily on the number of supporting floors and the rigidity of each floor

at the relevant time, are given in references cited in AS 3610, Supplement 2.


119 AS 2327.1—2003


APPENDIX G

DESIGN FOR FIRE RESISTANCE OF CONCRETE SLABS

(Normative)

G1 DEFINITIONS

For the purpose of this Appendix, the definitions given in Clause 10.2 shall apply.

G2 SOLID SLABS

Solid slabs shall be designed to achieve their required fire-resistance level in accordance with

AS 3600.

G3 COMPOSITE SLABS

Composite slabs shall be designed to achieve their required fire-resistance level in terms of

structural adequacy, insulation and integrity.

The period of structural adequacy of a composite slab shall be predicted by a recognized

method of calculation (see Note).

A composite slab shall be deemed to have one of the fire-resistance periods for insulation

given in Table G1, if the overall depth of the slab (Dc) is not less than the appropriate value

given in the Table.

TABLE G1

REQUIREMENTS FOR INSULATION PERIOD OF COMPOSITE SLAB

Minimum slab depth (Dc) mm Fire-resistance

period (minutes) Normal weight concrete Lightweight concrete

60 90 90

90 100 100

120 120 115

180 140 135

240 170 150

A composite slab shall be deemed to have integrity maintained for a particular fire-resistance

period provided the profiled steel sheeting forms a continuous membrane with the lap joints

being cast into and sealed by the concrete.

NOTE: An acceptable method of calculation is given in Reference 7, Appendix I.


AS 2327.1—2003 120


APPENDIX H

INFORMATION FOR DETERMINATION OF ACTION EFFECTS

(Informative)

H1 SUPPORT REACTION POSITIONS

For the purpose of determining the effective span of a composite beam, the support reaction

may be assumed to act in one of the following positions:

(a) When the steel beam is supported on a wall or plinth, the end reaction shall be assumed

to be at the lesser of Ds/2 or bs/2 in from the front face of the support (Figure H1(a)).

(b) When the steel beam is attached through a simple steel connection to a relatively rigid

wall or column, the end reaction shall be assumed to be at the face of the supporting

member (Figure H1(b)).

(c) When the steel beam is attached through a steel connection to a flexible wall or

column, the end reaction shall be assumed to be at the centre of the supporting member

(Figure H1(c)).

(d) When the steel beam is connected to the web of a supporting steel beam, the end

reaction shall be assumed to be at the centre of the supporting member (Figure H1(d)).

FIGURE H1 (in part) ASSUMED POSITION OF END SUPPORT REACTIONS OF A

COMPOSITE BEAM


121 AS 2327.1—2003


FIGURE H1 (in part) ASSUMED POSITION OF END SUPPORT REACTIONS OF A

COMPOSITE BEAM

H2 TRIBUTARY AREAS

The area of formwork or slab contributing load to a beam may be taken as one of the

following as appropriate:

(a) A solid slab shall be assumed to exhibit two-way action (Figure H2(a)).

(b) A composite slab shall be assumed to exhibit one-way action in the direction of the

sheeting ribs (Figure H2(b)).

(c) The presence of any props supporting a composite slab from below shall be considered

(Figure H2(c)).


AS 2327.1—2003 122


FIGURE H2 TRIBUTARY AREAS FOR STRENGTH LIMIT STATE


123 AS 2327.1—2003


APPENDIX I

BIBLIOGRAPHICAL REFERENCES

(Informative)

Attention is drawn to the following documents referred to in various Notes:

1 PATRICK M., DAYAWANSA P.H., WILKIE R. AND WATSON K.B., Partial Shear

Connection Strength Design of Simply-Supported Composite Beams—Draft Revision

of AS 2327, Part 1. Steel Construction, Australian Institute of Steel Construction,

Sydney, March 1994, pp 2-23.

2 PATRICK M. and WILKIE R., Tubeline and DuraGal Structural Steel Hollow-Section

Composite Beams. BHP Research Report No. BHPR/SM/R/013, March 1995.

3 PATRICK M., EADIE I. AND WATSON K.B., Development of a Suitable Semi-

Rigid Composite Connection. 4th Pacific Structural Steel Conference, Singapore,

October 1995.

4 WYATT T.A., Design Guide on the Vibration of Floors. Publication 076, The Steel

Construction Institute (UK), Ascot, Berks, 1989.

5 PATRICK M., DAYAWANSA P.H. and WATSON K.B., A New Reinforcing

Component for Preventing Longitudinal Shear Failure of Composite Edge-Beams. 4th

Pacific Structural Steel Conference, Singapore, October 1995.

6 PATRICK M., et al., Australian Composite Structures Standard AS 2327, Part 1:

Simply-Supported Beams. Steel Construction, Australian Institute of Steel

Construction, Vol. 29, No. 4, December 1995, pp. 2-40.

7 BENNETTS I.D., PROE D.J., PATRICK M. AND POON S.L., Design for Fire

Resistance of Composite Slabs Incorporating BONDEK II. 1994 Australasian

Structural Engineering Conference, Sydney, September 1994, Vol. 2, pp 651-656.

8 Composite Beam Design and Safe Load Tables. Australian Institute of Steel

Construction, Sydney 1989.

9 CHICK DAYAWANSA, D and PATRICK, M, ‘Strength Design of Simply-Supported

Composite Beams with Large Steel Web Penetrations’, Proceedings, Australasian

Structural Engineering Conference (ASEC-98), Auckland, September, 1998, pp159-

166.

10 MURRAY T.M., ALLAN, D.E. and UNGAR E.E., Floor Vibrations Due to Human

Activity, American Institute of Steel Construction and Canadian Institute of Steel

Construction, 1997.


AS 2327.1—2003 124

NOTES

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