5100.2-2004

AS 5100.22004

AP-G15.2/04 (Incorporating Amendment No. 1)

Australian Standard

Bridge design

Part 2: Design loads

AS

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This Australian Standard was prepared by Committee BD-090, Bridge Design. It was approved on behalf of the Council of Standards Australia on 4 November 2003. This Standard was published on 23 April 2004.

The following are represented on Committee BD-090:

Association of Consulting Engineers Australia Australasian Railway Association Austroads Bureau of Steel Manufacturers of Australia Cement and Concrete Association of Australia Institution of Engineers Australia Queensland University of Technology Steel Reinforcement Institute of Australia University of Western Sydney

This Standard was issued in draft form for comment as DR 00375. Standards Australia wishes to acknowledge the participation of the expert individuals that contributed to the development of this Standard through their representation on the Committee and through the public comment period.

Keeping Standards up-to-date Australian Standards are living documents that reflect progress in science, technology and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments that may have been published since the Standard was published. Detailed information about Australian Standards, drafts, amendments and new projects can be found by visiting www.standards.org.au Standards Australia welcomes suggestions for improvements, and encourages readers to notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at [email protected], or write to Standards Australia, GPO Box 476, Sydney, NSW 2001.

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AS 5100.22004

AP-G15.2/04 (Incorporating Amendment No. 1)

Australian Standard

Bridge design


Originated as HB 77.21996. Revised and redesignated as AS 5100.22004. Reissued incorporating Amendment No. 1 (April 2010).

COPYRIGHT

Standards Australia

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 GPO Box 476, Sydney, NSW 2001, Australia

ISBN 0 7337 5628 X

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AS 5100.22004 2

PREFACE

This Standard was prepared by the Standards Australia Committee BD-090, Bridge Design,

to supersede HB 77.21996, Australian Bridge Design Code, Section 2: Design loads.

This Standard incorporates Amendment No. 1 (April 2010). The changes required by the

Amendment are indicated in the text by a marginal bar and amendment number against the

clause, note, table, figure or part thereof affected.

The AS 5100 series represents a revision of the 1996 HB 77 series, Australian Bridge

Design Code, which contained a separate Railway Supplement to Sections 1 to 5, together

with Section 6, Steel and composite construction, and Section 7, Rating. AS 5100 takes the

requirements of the Railway Supplement and incorporates them into Parts 1 to 5 of the

present series, to form integrated documents covering requirements for both road and rail

bridges. In addition, technical material has been updated.

This Standard is also designated as AUSTROADS publication AP-G15.2/04.

The objectives of AS 5100 are to provide nationally acceptable requirements for

(a) the design of road, rail, pedestrian and bicycle-path bridges;

(b) the specific application of concrete, steel and composite construction, which embody

principles that may be applied to other materials in association with relevant

Standards; and

(c) the assessment of the load capacity of existing bridges.

These requirements are based on the principles of structural mechanics and knowledge of

material properties, for both the conceptual and detailed design, to achieve acceptable

probabilities that the bridge or associated structure being designed will not become unfit for

use during its design life.

Whereas earlier editions of the Australian Bridge Design Code were essentially

administered by the infrastructure owners and applied to their own inventory, an increasing

number of bridges are being built under the design-construct-operate principle and being

handed over to the relevant statutory authority after several years of operation. This

Standard includes Clauses intended to facilitate the specification to the designer of the

functional requirements of the owner to ensure the long-term performance and

serviceability of the structure.

Significant differences between this Standard and HB 77.2 are the following:

(i) Highway bridge design loads The design model for road traffic loads has been

completely redefined to make provision for potential future increases in legal load

limits. Not only does the design load reflect the projected increased loads but it has

also been modified so that it more closely represents the full spectrum of vehicle

configurations and traffic patterns. It no longer looks like a semi-trailer but is

purely a mathematical model. This new model incorporates both moving traffic loads

and stationary traffic loads, and also incorporates the effects of special vehicles. The

width of the design load, the standard design load and the standard design lane have

been increased to 3.2 m, to reflect future loads and truck configurations. Provision

has been made for the heavy load platform (HLP) design load, which may be

specified by the relevant authority if required.

(ii) Dynamic load allowance The dynamic load allowance for railway bridges has been

modified to incorporate the results of experience and investigations of fatigue in

transom top steel railway bridges. The dynamic load allowance for road bridges has

been adapted to reflect the recent changes in the Canadian Highway Bridge Design

Code, modified to suit Australian conditions.

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3 AS 5100.22004

(iii) Bridge barriers The clauses for design loads of road bridge barriers have been

updated to be consistent with performance level definition and selection specified in

AS 5100.1. Many of the clauses are based on recently developed AASHTO*

documentation, suitably modified to reflect local Australian conditions.

(v) Earthquake loading The earthquake loading clause has been updated to reflect the

intent of AS 1170.4 as applicable to bridges.

In line with Standards Australia policy, the words shall and may are used consistently

throughout this Standard to indicate, respectively, a mandatory provision and an acceptable

or permissible alternative.

Statements expressed in mandatory terms in Notes to Tables are deemed to be requirements

of this Standard.

The term informative has been used in this Standard to define the application of the

appendix to which it applies. An informative appendix is only for information and

guidance.

* American Association of State Highway and Transportation Officials

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AS 5100.22004 4

CONTENTS

Page

1 SCOPE AND GENERAL ........................................................................................... 5

2 REFERENCED DOCUMENTS.................................................................................. 6

3 DEFINITIONS............................................................................................................ 6

4 NOTATION................................................................................................................ 6

5 DEAD LOADS ......................................................................................................... 10

6 ROAD TRAFFIC ...................................................................................................... 12

7 PEDESTRIAN AND BICYCLE-PATH LOAD ........................................................ 21

8 RAILWAY TRAFFIC............................................................................................... 22

9 MINIMUM LATERAL RESTRAINT CAPACITY .................................................. 30

10 COLLISION LOADS ............................................................................................... 31

11 KERB AND BARRIER DESIGN LOADS AND OTHER REQUIREMENTS FOR

ROAD TRAFFIC BRIDGES .................................................................................... 33

12 DYNAMIC BEHAVIOUR........................................................................................ 37

13 EARTH PRESSURE................................................................................................. 40

14 EARTHQUAKE FORCES........................................................................................ 42

15 FORCES RESULTING FROM WATER FLOW ...................................................... 48

16 WIND LOADS ......................................................................................................... 57

17 THERMAL EFFECTS.............................................................................................. 60

18 SHRINKAGE, CREEP AND PRESTRESS EFFECTS ............................................. 64

19 DIFFERENTIAL MOVEMENT OF SUPPORTS ..................................................... 64

20 FORCES FROM BEARINGS................................................................................... 65

21 CONSTRUCTION FORCES AND EFFECTS.......................................................... 65

22 LOAD COMBINATIONS ........................................................................................ 66

23 ROAD SIGNS AND LIGHTING STRUCTURES .................................................... 67

24 NOISE BARRIERS .................................................................................................. 69

APPENDIX A DESIGN LOADS FOR MEDIUM AND SPECIAL PERFORMANCE

LEVEL BARRIERS.................................................................................. 71

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5 AS 5100.22004

www.standards.org.au Standards Australia

STANDARDS AUSTRALIA

Australian Standard

Bridge design


1 SCOPE AND GENERAL

1.1 Scope

This Standard sets out minimum design loads, forces and load effect for road, railway,

pedestrian and bicycle bridges, and other associated structures.

1.2 General

Structures shall be proportioned for the design loads, forces and load effects in accordance

with Clauses 5 to 24, as appropriate.

NOTE: If the authority approves, the designer may vary any of the loads set out in this Standard

on the basis of engineering measurements and calculations, provided the provisions of AS 5100.1

are complied with.

The design loads and forces shall be considered as acting in combinations as set out in

Clause 22.

Each individual bridge shall be assessed to ascertain whether any other loads, forces or load

effects are applicable for that particular design. The magnitude of these additional forces or

load effects, and their combination with other loads shall be consistent with the principles

set out in AS 5100.1.

On the front sheet of the bridge drawings, the following details relating to design loads

shall be shown where relevant:

(a) The Standard used.

(b) Any significant variation to the minimum design loads as set out in this Standard.

(c) Traffic load, e.g., 300LA and SM1600, including lateral position, if critical, and the

number of design lanes.

(d) Design traffic speed.

(e) Fatigue criteria, including number of cycles and route factor.

(f) Pedestrian load.

(g) Collision load on piers, where applicable, or alternative load paths provided.

(h) Design wind speeds.

(i) Flood data, e.g., design velocities, levels, debris, and the like.

(j) Earthquake zone.

(k) Differential settlements and mining subsidence effects allowed for in the design.

(l) Foundation data where not shown elsewhere.

(m) Barrier performance level.

Where required, the construction methods and sequence, or any other specific limitations,

shall be indicated on the bridge drawings. Acce

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AS 5100.22004 6

Standards Australia www.standards.org.au

2 REFERENCED DOCUMENTS

The following documents are referred to in this Standard:

AS

1170 Minimum design loads on structures

1170.4* Part 4: Earthquake loads

1726 Geotechnical site investigations

4678 Earth-retaining structures

5100 Bridge design

5100.1 Part 1: Scope and general principles

5100.3 Part 3: Foundations and soil-supporting structures

5100.4 Part 4: Bearings and deck joints

5100.5 Part 5: Concrete

5100.6 Part 6: Steel and composite construction

5100.7 Part 7: Rating of existing bridges

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

Austroads Vehicle Classification Scheme

TRB-NCHRP 350 Recommended Procedures for the Safety Performance Evaluation of

Highway Features

3 DEFINITIONS

For the purpose of this Standard, the definitions in AS 5100.1 apply.

4 NOTATION

The symbols used in this Standard are listed in Table 4.

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

expressed in identical units.

The units for length and load in all expressions or equations are to be taken as metres (m)

and kilonewtons (kN) respectively, unless specifically noted otherwise. The unit for

velocity is in metres per second, unless specified otherwise.

An asterisk (*) placed after a symbol as a superscript denotes a design action effect due to

the design load for either the ultimate limit state or the serviceability limit state.

* This Standard refers to the superseded 1993 edition of AS 1170.4 and not to the current

edition of AS 1170.4, published in 2007.

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TABLE 4

NOTATION

Symbols Description Clause reference

A axle load 8.6.1

Ad area, equal to the thickness of the pier normal to the

direction of the water flow, multiplied by the height of the

water flow

15.3.1

Adeb projected area of debris 15.5.4

AL area, equal to the width of the pier parallel to the direction

of the water flow, multiplied by the height of the flow; or

plan deck area of the superstructure

15.3.2

15.4.3

Ap bridge area in plan 16.5

As wetted area of the superstructure, including any railings or

parapets, projected on a plane normal to the water flow; or

projected area of debris

15.4.2 and 15.4.4

At area of the structure for calculation of wind load 16.3.1

a acceleration coefficient 14.3.3

b width between traffic barriers; or

overall width of the bridge between outer faces of parapets

6.5

16.3.3

C earthquake design coefficient 14.5.4

Cd drag coefficient 15.3.1

Ch earthquake design coefficient 14.5.7

CL lift coefficient 15.3.2

Cm moment coefficient 15.4.4

CT base number of load cycles 8.7.4

d depth of the superstructure, including solid parapet, if

applicable

16.3.3

dsp wetted depth of the superstructure (including any railings

or parapets) projected on a plane normal to the water flow

(see Figure 15.4.2(B))

15.4.2

dss wetted depth of the solid superstructure, excluding any

railings but including solid parapets, projected on a plane

normal to the water flow

15.4.2

dwgs vertical distance from the girder soffit to the flood water

surface upstream of the bridge

15.4.2

F Froude number 15.5.4(B)

FBM braking force applied by multiple vehicles 6.8.2

FBS braking force applied by a single vehicle 6.8.2

Fc centrifugal force 6.8.1

FL ultimate longitudinal or transverse inward load 12.3

FT ultimate transverse outward load 12.3

FV ultimate vertical downward load 12.3

*dsF serviceability design drag force 15.3.1

*duF ultimate design drag force 15.3.1

*LsF serviceability design lift force 15.3.2

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AS 5100.22004 8



*LuF ultimate design lift force 15.3.2

f* fatigue design stress range 8.7.3

GB distance of wheel load to the track centre-line 10.5.2

Gg total unfactored dead load including superimposed dead

load 14.5.2

g acceleration due to gravity 6.8.1

HCF centrifugal force resulting from railway loads 8.6.1

He minimum effective height Table 11.2.3

*uH horizontal design earthquake force 14.5.2

h height of the top rail; or

depth of fill cover, in millimetres

11.5

6.12

hd average height of the columns or piers supporting the

superstructure length (Ld)

14.7.3

k coefficient 22.3

I importance factor 14.5.3

L effective span; or

loaded length; or

span of the member between posts

6.9

8.6.2

11.5

Lbs minimum support length measured normal to the face of an

abutment or pier

14.7.3

Ld length of the superstructure to the next expansion joint 14.7.3

Lf span of main girders, trusses or stringers; or

cross-girder spacing for cross-girders

8.7.4

LL vehicle contact length for longitudinal loads 11.3

Lmax. largest of the values L1, L2, Ln 8.4.2

LT vehicle contact length for transverse loads 11.3

Lv distance between centres of axle groups; or

vehicle contact length for vertical loads

8.7.1

12.3

L1, L2, Ln span lengths of a continuous structure 8.4.2

L characteristic length 8.4.1

Mi importance factor 24.2

Ms shielding multiplier 24.1.4

*gsM serviceability design superstructure moment 15.4.4

*guM ultimate design superstructure moment 15.4.4

mi discrete mass 14.5.4

n number of standard design loads; or

effective number of cycles; or

number of continuous main girder spans

6.5

8.7.4

Table 8.4.2

nT number of equivalent stress cycles of amplitude (f*) per

train, which depends on Lf and Lv

8.7.4

Pr proximity ratio 15.4.2

pn net pressure for hoardings and freestanding walls 24.5

q* design wind pressure 23.4

(continued)

TABLE 4 (continued)

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Rf structural response factor 14.5.5

r radius of curve 8.6.1

S site factor 14.3.4

Sr relative submergence 15.4.2

T structure period of the first dominant mode of free

vibration, in the direction under consideration; or

temperature

14.5.4

Figure 17.3

V design speed 8.6.1

Vs mean velocity of water flow for serviceability limit states

at the level of the superstructure or debris as appropriate;

or

design wind speed for serviceability limit states

15.3.1

16.3

Vu mean velocity of water flow for ultimate limit states at the

level of the superstructure or debris as appropriate

15.3.1

16.3

Vw design wind speed for the ultimate limit states, or

serviceability limit state

23.4

v operating speed 6.8.1

WBM load due to multiple lanes of the M1600 moving traffic

load for the length under consideration

6.8.2

WBS load due to a single lane of the M1600 moving traffic load

for the length under consideration, up to a maximum of

1600 kN

6.8.2

Wc load due to multiple lanes of the M1600 moving traffic

load for the length under consideration

6.8.1

*tsW serviceability design transverse wind load 16.3

*tuW ultimate design transverse wind load 16.3

*vsW serviceability design vertical wind load 16.5

*vuW ultimate design vertical wind load 16.5

y average flow depth 15.5.4(A)

ygs average vertical distance from the girder soffit to the bed

assuming no scour at the span under consideration

15.4.2

dynamic load allowance 6.7.2

displacement under self weight 14.5.4

g load factor for dead load 5.2

ge load factor for the density of soils and groundwater 5.4

gb load factor for railway ballast and track loads 5.5

gs load factor for superimposed dead load 5.3

LL load factor for live load 10.4.4

WF ultimate load factor for water flow 15.2.1

superelevation of the road 6.8.1

s angle of skew of the support measured from a line normal to the span

14.7.3

w angle between the direction of the water flow and the transverse centre-line of the pier

Figure 15.3.1

TABLE 4 (continued)

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AS 5100.22004 10


5 DEAD LOADS

5.1 General

The nominal dead load shall be calculated from the dimensions shown on the drawings and

the mean value of the weight per unit volume of the materials. A figure based on the

densities of the materials, the percentage of reinforcement and other appropriate factors

shall be adopted. Wherever possible, design densities shall be based on measurements of

the materials to be used.

Selecting a high value of density may be conservative when considering some limit states,

but may not be conservative when considering stability, stresses at transfer of prestress and

the like. If insufficient information is available to accurately assess the mean weight per

unit volume, calculations shall be performed using a range of values and the most critical

case shall be used for the design.

5.2 Dead load of structure

Dead load shall be considered as the weight of the parts of the structure that are structural

elements and any non-structural elements that are considered unlikely to vary during

construction and use of the structure, such as parapets and kerbs of steel or concrete.

To obtain the design dead loads for ultimate and serviceability limit states, the nominal

dead load shall be multiplied by the appropriate load factor (g) given in Table 5.2.

For all types of structures, except structures of balanced cantilever or anchor cantilever

design, or similar, the appropriate value of g shall be applied to the dead load of all parts of

the structure. For the exceptions, the values of g given in Item (b) or Item (c) of Table 5.2

for unfavourable or favourable dead load shall be applied to the appropriate parts of the

structure.

TABLE 5.2

LOAD FACTORS (g) FOR DEAD LOAD OF STRUCTURE

Ultimate limit states

where dead load Type of structure

Type of

construction Reduces

safety

Increases

safety

Serviceability

limit states

(a) All structures, except for Items (b) and (c) Steel

Concrete

1.1

1.2

0.9

0.85

1.0

1.0

(b) Balanced cantilever structures At a

section subjected to approximately equal

favourable and unfavourable dead loads

All 1.1 1.0 1.0

(c) Anchor cantilever structures At a section

subjected to unequal favourable and

unfavourable dead loads

All 1.2 1.0 1.0

NOTE: For large segmental cantilever construction, where appropriate control and monitoring are exercised

over dimensions, the authority may allow a reduction of g to not less than 1.1 for ultimate limit states, for

the case where the dead load reduces safety.

5.3 Superimposed dead load

Superimposed dead load shall be considered as the weight of all materials forming the loads

on the structure, which are not structural elements and which vary during construction and

use of the structure.

NOTE: Examples of superimposed dead load include surfacing material, footway filling, tram

tracks, pipes, conduits, cables and other utility services, and additional concrete to compensate

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If a separate wearing surface is to be placed when the bridge is constructed or if placement

of a separate wearing surface is anticipated in the future, allowance shall be made for its

weight in the superimposed dead load.

The design superimposed dead loads for ultimate and serviceability limit states shall be

obtained by applying the appropriate load factor (gs), given in Table 5.3, to the nominal

superimposed dead loads on the structure.

For special cases, and subject to the approval of the relevant authority, the values of gs to

be applied to the nominal superimposed dead load may be reduced to an amount not less

than those given in Item (b) of Table 5.3. It shall be ensured that the nominal superimposed

dead load is not exceeded during the life of the bridge.

TABLE 5.3

LOAD FACTORS (gs) FOR SUPERIMPOSED DEAD LOAD (SDL)

Ultimate limit states

where SDL Type of structure Type of load

Reduces

safety

Increases

safety

Serviceability

limit states

(a) All structures, except for Item (b) Permanent

Removable

2.0

2.0

0.7

0

1.3

1.3

(b) Special cases On major structures where

superimposed dead loads are controlled by

the relevant authority.

Permanent

Removable

1.4

1.4

0.8

0

1.0

1.0

5.4 Soil loads on retaining walls and buried structures

Soil loads and properties of the soil shall be obtained from AS 4678. The design of

foundations and soil-supporting structures shall be carried out in accordance with this

Standard and AS 5100.3. Where required during the design, the density of soils shall be

factored by the load factor (ge) given in Table 5.4.

TABLE 5.4

LOAD FACTORS (ge) FOR THE DENSITY OF SOILS AND GROUNDWATER

Ultimate limit states where soil Type of soil

Increases load Reduces load

Serviceability

limit state

Controlled fill with regular testing of soil density 1.25 0.85 1.0

All other fills and in-situ soils 1.5 0.7 1.2

Groundwater 1.0 1.0 1.0

NOTE: Variation in water levels shall be taken into account by using design levels based on a return period

of 1000 years for the ultimate limit state or 100 years for the serviceability limit state.

5.5 Railway ballast and track loads

Railway ballast and track shall be considered as removable superimposed dead loads. The

design loads for the ultimate and serviceability limit states shall be obtained by applying the

appropriate load factor (gb) given in Table 5.5 to the nominal ballast and track loads.

For bridges such as half through structures, if it is possible to fill with ballast to a much

greater depth than normally specified, the maximum amount of ballast possible on the

bridge shall also be determined and the nominal amount of ballast shall be taken as not less

than 0.7 times that maximum amount.

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TABLE 5.5

LOAD FACTORS (gb) FOR RAILWAY BALLAST AND TRACK LOADS

Ultimate limit states where load Type of

structure Type of load

Reduces safety Increases safety

Serviceability

limit states

Ballast and track 1.7 0.7 1.3 All structures

Transom track 1.4 0.9 1.2

6 ROAD TRAFFIC

6.1 General

Road traffic load is the load resulting from the passage of vehicles, either singly or in

groups, or pedestrians. The magnitude, direction and positioning of loads in this Standard

produce effects in structures that approximate the effects of vehicles or groups of vehicles.

The load models are not intended to be the same as actual vehicles.

6.2 SM1600 loads

The abbreviation SM1600 represents the design loads W80, A160, M1600 and S1600 traffic

design loads.

All road bridges shall be designed to resist the following:

(a) The traffic loads specified in this Standard, which approximate the effects induced by

moving traffic, stationary queues of traffic and pedestrian traffic.

(b) The most adverse effects induced by the following loading elements, combinations of

these elements and their corresponding load factors:

(i) W80 wheel load.

(ii) A160 axle load.

(iii) M1600 moving traffic load.

(iv) S1600 stationary traffic load.

(v) HLP320 or HLP400, if required by the authority.

(vi) Dynamic load allowance ().

(vii) Number and position of traffic lanes.

(viii) Accompanying lane factors (ALF).

(ix) Centrifugal forces (Fc).

(x) Braking forces (FBS, FBM).

(xi) Fatigue load.

(xii) Pedestrian load.

6.2.1 W80 wheel load

The W80 wheel load models an individual heavy wheel load. It shall consist of an 80 kN

load uniformly distributed over a contact area of 400 mm 250 mm. The W80 wheel load

shall be applied anywhere on the roadway surface and to all structural elements for which

the critical load is a single wheel load.

6.2.2 A160 axle load

The A160 load models an individual heavy axle. It shall consist of the load shown in

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FIGURE 6.2.2 A160 AXLE LOAD

6.2.3 M1600 moving traffic load

The M1600 moving traffic load models the loads applied by a moving stream of traffic. The

M1600 load shall be positioned laterally within a 3.2 m standard design lane as shown in

Figure 6.2.3.

The moving traffic load shall consist of a uniformly distributed load together with a truck

load as shown in Figure 6.2.3. The uniformly distributed component of the M1600 moving

traffic load continues under the truck and shall be considered as uniformly distributed over

the width of a 3.2 m standard design lane.

The uniformly distributed component of the M1600 moving traffic load shall be continuous

or discontinuous and of any length as may be necessary to produce the most adverse effects.

Likewise, the truck position and variable spacing shall be determined so as to produce the

most adverse effects.

Where a single tri-axial group from the M1600 moving traffic load, including the UDL

component, controls, the dynamic load allowance () shall be as given in Table 6.7.2. The

UDL component shall be continuous or discontinuous and of any length as necessary to

produce the most adverse effects.

FIGURE 6.2.3 M1600 MOVING TRAFFIC LOAD

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AS 5100.22004 14


6.2.4 S1600 stationary traffic load

The S1600 stationary traffic load models the loads applied by a stationary queue of traffic.

The S1600 stationary traffic load shall consist of a uniformly distributed load together with

a truckload as shown in Figure 6.2.4. The uniformly distributed component of the S1600

stationary traffic load continues under the truck and shall be considered as uniformly

distributed over the width of a 3.2 m standard design lane. The S1600 truck shall be

positioned laterally within a 3.2 m standard design lane as shown in Figure 6.2.4.

The uniformly distributed component of the S1600 stationary traffic load shall be

continuous or discontinuous and of any length as may be necessary to produce the most

adverse effects. Likewise, the truck position and variable spacing shall be determined so as

to produce the most adverse effects.

FIGURE 6.2.4 S1600 STATIONARY TRAFFIC LOAD

6.3 Heavy load platform

The heavy load platform design load HLP320 or HLP400, or an alternative platform design

load, may be specified by the authority. Details of HLP320 and HLP400 load configurations

are specified in AS 5100.7.

The HLP320 and HLP400 heavy load platform loads shall be assumed to centrally occupy

two standard design lanes or the road carriageway width, whichever is the lesser.

The heavy load platform loads shall be positioned laterally on a bridge as specified by the

authority. To account for errors in the positioning of actual vehicles, bridges shall be

designed for the effects of the heavy load platform loads positioned up to 1.0 m laterally in

either direction from the specified position.

Where the two standard design lanes containing the heavy load platform loads are

positioned such that one or more design traffic lanes are unobstructed, then a load of half of

either the M1600 moving traffic load or the S1600 stationary traffic load, to create the

worst effect, shall be placed in those lanes, unless the authority specifies otherwise.

6.4 Tramway and railway loads

Where road bridges are to carry tramway or railway traffic, the operating authority for the

utility shall be consulted to determine the appropriate design loads and load factors.

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6.5 Number of lanes for design and lateral positioning

The A160, M1600 and S1600 loadings shall be assumed to occupy one standard design lane

of 3.2 m width. The number and position of standard design lanes shall be as follows:

2.3

bn = (rounded down to next integer) . . . 6.5

where

n = number of standard design loads

b = width between traffic barriers, in metres, unless specified otherwise

These standard design lanes shall be positioned laterally on the bridge to produce the most

adverse effects.

6.6 Accompanying lane factors

If more than one lane is loaded, the A160, M1600 or S1600 loading applied to the

additional lanes shall be multiplied by the accompanying lane factors given in Table 6.6.

TABLE 6.6

ACCOMPANYING LANE FACTORS

Standard design lane number, n Accompanying lane factor, ALFi

1 lane loaded 1.0

2 lanes loaded 1.0 for first lane; and

0.8 for second lane

3 or more lanes loaded 1.0 for first lane;

0.8 for second lane; and

0.4 for third and subsequent lanes

NOTES:

1 First lanethe loaded lane giving the largest effect.

2 Second lanethe loaded lane giving the second largest effect.

3 Third lanethe loaded lane giving the third largest effect.

The number of standard design lanes loaded and the load patterning (standard design lane

numbering) shall be selected to produce the most adverse effects.

For bridges that support vehicle and pedestrian traffic, the accompanying load factors shall

be applied to both the vehicle and the pedestrian traffic. The total pedestrian load shall be

considered as one standard design lane.

6.7 Dynamic load allowance

6.7.1 General

The dynamic load allowance () set out in this Clause specifies an increase in the traffic

load resulting from the interaction of moving vehicles and the bridge structure, and shall be

described in terms of the static equivalent of the dynamic and vibratory effects. For design

purposes, shall be specified as a proportion of the traffic load and shall be applied as

specified in Clause 6.7.2. The dynamic load allowance applies to both the ultimate and

serviceability limit states.

The dynamic load allowance models the dynamic effects of vehicles moving over bridges

with typical road profile irregularities.

6.7.2 Magnitude

The design action is equal to (1 + ) the load factor the action under consideration.

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The value of for the appropriate loading shall be as given in Table 6.7.2.

For deck joints, the values for specified in AS 5100.4 shall be used.

TABLE 6.7.2

DYNAMIC LOAD ALLOWANCE ()

Loading Dynamic load allowance ()

W80 wheel load 0.4

A160 axle load 0.4

M1600 tri-axle group (see Note 2) 0.35

M1600 load (see Note 2) 0.30

S1600 load (see Note 2) 0

HLP loading 0.1

NOTES:

1 Dynamic load allowance is not required for centrifugal forces,

braking forces or pedestrian load.

2 Including the UDL component of the traffic load.

6.7.3 Application

The dynamic load allowance shall be applied to all parts of the structure extending down to

the ground level.

For parts of the structure below the ground level, the dynamic load allowance to be applied

to each part shall be

(a) the ground level value for a cover depth of zero;

(b) zero for a cover depth of 2 m or more; or

(c) a linear interpolation between depths of zero and 2 m.

For buried structures such as culverts and soil-steel structures, the dynamic load allowance

to be applied to the entire structure shall be

(i) the ground level value for a cover depth of zero;

(ii) 0.1 for a cover depth of 2 m or more for loads excluding S1600. For S1600 loads, the

dynamic load allowance is zero; or

(iii) a linear interpolation between depths of zero and 2 m.

6.7.4 Dynamic load reversal

Consideration shall be given to the reversal of the dynamic response to live load. Vibrations

may continue and slowly decay after passing of traffic. In particular, the minimum reaction

on bearings shall take into consideration any reduction that may occur as a result of

dynamic effects.

6.8 Horizontal forces

6.8.1 Centrifugal forces

For bridges on horizontal curves, allowance shall be made for the centrifugal effects of

traffic load on all parts of the structure. The bridge shall be designed to resist the most

adverse co-existing effects induced by the M1600 moving traffic load and the centrifugal

force (Fc), in kilonewtons.

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The centrifugal force (Fc) shall be assumed to act at deck level and shall be applied in

accordance with the distribution of load in the M1600 moving traffic load. The centrifugal

force (Fc) shall be calculated as follows:

c

2

cW

rg

VF = . . . 6.8.1(1)

( ) c 0.35 W+ . . . 6.8.1(2)

where

V = design speed, in metres per second

r = radius of curve, in metres

g = acceleration due to gravity (9.81 m/s2)

Wc = load due to multiple lanes of the M1600 moving traffic load for the length

under consideration, in kilonewtons. No dynamic load allowance is to be

considered.

Accompanying lane factors shall be applied, i.e.

= i i

j

1 i

M1600ALF =

. . . 6.8.1(3)

j = number of design lanes

ALFi = accompanying lane factor (see Table 6.6)

= superelevation of the road, expressed as a ratio, e.g., 4% superelevation is

expressed as 0.04

6.8.2 Braking forces

Braking effects of traffic shall be considered as a longitudinal force. Braking forces shall be

applied in either direction. The restraint system shall be designed to resist the most adverse

co-existing effects induced by the braking force and the vertical traffic load. The braking

force shall be applied in accordance with the distribution of mass of the vertical traffic load.

The braking force shall be assumed to act at the road surface. The most adverse effects from

the following scenarios shall be considered:

(a) Single vehicle stopping The braking force for single vehicle stopping (FBS) shall be

calculated as follows:

BSBS45.0 WF = . . . 6.8.2(1)

200 kN < FBS < 720 kN

where

FBS = braking force applied by a single vehicle

WBS = load due to a single lane of the M1600 moving traffic load for the

length under consideration, in kilonewtons, up to a maximum of

1600 kN. No dynamic load allowance is to be included

FBS shall be applied to any lane of a multi-lane bridge to produce the most adverse

effects.

(b) Multi-lane moving traffic stream stopping The braking force for multi-lane moving

traffic stream stopping (FBM) shall be calculated as follows:

BMBM15.0 WF = . . . 6.8.2(2)

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where

FBM = braking force applied by multiple vehicles

WBM = load due to multiple lanes of the M1600 moving traffic load for the

length under consideration, in kilonewtons. No dynamic load

allowance is to be included.

Accompanying lane factors shall be applied, i.e.

= i i

j

1 i

M1600ALF =

. . . 6.8.2(3)

The number of lanes to be included shall be limited to those likely to carry traffic in a

single direction, unless specified otherwise by the relevant authority.

When assessing the effects of longitudinal forces on bridge bearings and substructures, the

friction or shear displacement characteristics of expansion bearings and the stiffness of the

substructure shall be taken into account.

6.9 Fatigue load effects

The fatigue design traffic load effects shall be determined from 70% of the effects of a

single A160 axle or 70% of a single M1600 moving traffic load, without UDL, whichever is

more severe. In both cases, a load factor of 1.0 shall be used and the load effects shall be

increased by the dynamic load allowance ().

The single A160 axle load or M1600 moving traffic load, without UDL, shall be placed

within any design traffic lane to maximize the fatigue effects for the component under

consideration.

Unless determined otherwise by the relevant authority, the number of fatigue stress cycles

to be used for the calculation of the fatigue capacity of the structural element under

consideration shall be as follows:

(a) For the fatigue design load of 0.70 (A160 axle load) (1 + ):

(current number of heavy vehicles per lane per day) 4 104 (route factor).

(b) For the fatigue design load of 0.70 (M1600 moving traffic load without UDL)

(1 + ):

(current number of heavy vehicles per lane per day) 2 104(L

0.5) (route factor).

Unless specified otherwise by the relevant authority, the route factor shall be

(i) for principal interstate freeways and highways ..................................................... 1.0;

(ii) for urban freeways............................................................................................... 0.7;

(iii) for other rural routes......................................................................................0.5; and

(iv) for urban roads other than freeways...................................................................... 0.3.

On interstate and other rural routes where there are two or more lanes in one direction, the

number of heavy vehicles per lane per day shall be the total of the heavy vehicles travelling

in that direction. On urban routes where there are two or more lanes in one direction, the

number of heavy vehicles per lane per day shall be 65% of the total number of heavy

vehicles in that direction.

The fatigue design traffic load effects and relevant stress cycles shall be applied to each

design lane independently.

L is the effective span in metres and is defined as follows:

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(A) For positive bending moments, L is the actual span in which the bending moment is

being considered.

(B) For negative moment over interior supports, L is the average of the adjacent spans.

(C) For end shear, L is the actual span.

(D) For reactions, L is the sum of the adjacent spans.

(E) For cross-girders, L is twice the longitudinal spacing of the cross-girders.

A fatigue stress cycle shall be taken to be the maximum peak to peak stress from the

passage of the relevant fatigue design load.

Heavy vehicles shall be as defined by the Austroads Vehicle Classification Scheme, i.e.,

Classes 3 to 12.

The current number of heavy vehicles shall be based on the year the bridge is to be put into

service.

This Clause does not apply to fatigue design of roadway expansion joints.

6.10 Load factors

For ultimate and serviceability limit state design loads, the load factors for design road

traffic loads shall be as given in Table 6.10(A).

TABLE 6.10(A)

LOAD FACTORS FOR DESIGN ROAD TRAFFIC LOADS

Limit state Traffic load

Ultimate Serviceability

W80 wheel load 1.8 1.0

A160 axle load 1.8 1.0

M1600 moving traffic load 1.8 1.0

S1600 stationary traffic load 1.8 1.0

Heavy load platform load 1.5 1.0

The load factor to be applied in calculating the design centrifugal and braking forces shall

be as given in Table 6.10(B).

TABLE 6.10(B)

LOAD FACTORS FOR DESIGN

CENTRIFUGAL AND BRAKING FORCES

Limit state Force


Centrifugal force 1.8 1.0

Braking force 1.8 1.0

Each of the design horizontal forces due to road traffic load shall be applied simultaneously

with the vertical road traffic load and such load cases or any combination thereof shall be

considered as a single vehicular traffic load specified in Clause 22.1.3.

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6.11 Deflection

The deflection limits of a road bridge under traffic for serviceability limit state shall be

appropriate to the structure and its intended use, the nature of the loading and the elements

supported by it.

Notwithstanding this requirement, the deflection for serviceability limit state under live

load plus dynamic load allowance shall be not greater than 1/600 of the span or 1/300 of the

cantilever projection, as applicable.

The live load to be used for calculating deflection shall be one M1600 moving traffic load,

without UDL, including dynamic load allowance, placed longitudinally in each design lane

to produce the maximum deflection, taking into account the accompanying lane factors.

NOTE: In calculating the deflection, the following assumptions may be made:

(a) The deflection of the bridge may be averaged across all beams.

(b) The design cross-section of the bridge may include continuous portions of road furniture

contributing to stiffness, provided that adequate connection is included to ensure composite

action with the bridge deck.

In addition, road traffic bridges shall be designed so that

(a) deflections do not infringe on clearance diagrams;

(b) hog deflection does not exceed 1/300 of the span; and

(c) no sag deflection occurs under permanent loads.

6.12 Distribution of road traffic loads through fill

For all types of roadway pavements above structures, the distribution of SM1600 design

loads, with the factors and allowances applied in accordance with this Standard, shall be as

specified below, unless calculated otherwise by an analytical modelling procedure approved

by the authority. This requirement shall apply to all types of roadway pavements.

SM1600 design wheel loads shall be distributed through the fill cover over the structure,

from the imprint of the rectangular wheel contact area at the road surface to a rectangular

distribution area on the surface of the structure, proportioned in accordance with the wheel

contact area dimensions.

The length of the sides of the distribution rectangle shall be determined as follows:

(a) For depths of fill cover from 0 to 200 mmsides of distribution rectangle = sides of

wheel contact rectangle + 0.5 h, where h is the depth of fill cover in millimetres.

(b) For depths of fill cover greater than 200 mmsides of distribution rectangle = sides

of wheel contact rectangles + 100 mm + 1.2 (h 200).

Where distribution areas from several wheel loads overlap, the total load may be considered

to be evenly distributed on the surface over the total area of distribution.

The uniformly distributed component of the SM1600 design load shall be applied with no

longitudinal distribution. Transverse distribution shall be as for wheel loads.

The total width of transverse distribution shall not exceed the total width of the structure

supporting the fill.

For single spans, the road traffic loads may be neglected when the depth of fill is more than

2.5 m and exceeds the span length. For multiple spans, road traffic loads may be neglected

when the depth of fill exceeds the distance between faces of the end abutments.

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7 PEDESTRIAN AND BICYCLE-PATH LOAD

7.1 General

Pedestrian and bicycle-path bridges, and walkways on road and railway traffic bridges that

provide public access shall be designed for the loads per square metre of loaded area as

shown in Figure 7.

The loaded area shall be the area related to the structural element under consideration.

Dynamic load allowance need not be applied to pedestrian load.

Road and rail traffic bridges with access walkways not intended for public use are not

required to be designed for the simultaneous occurrence of the road and railway live load

and the walkway live load.

Where it is possible for a vehicle, such as a park tractor, to mount the walkway, the

walkway shall be designed to carry a concentrated load of 20 kN, with no dynamic load

allowance, unless specified otherwise by the authority.

Where the authority requires that a pedestrian bridge or walkway be designed for crowd

loading, such as for special events, a design load of 5 kPa shall be used.

FIGURE 7 PEDESTRIAN LOADS

7.2 Service live load on walkways

For structures fitted with walkways or service platform, or both, a total load of 2.2 kN shall

be distributed over any 0.6 m length of walkway or platform, and multiplied by the load

factors given in Table 7.3 to obtain the appropriate design load.

7.3 Load factors

For ultimate and serviceability limit state design loads, the load factors for design

pedestrian loads shall be as given in Table 7.3.

NOTE: Where a pedestrian bridge is not located above a road or railway, the authority may

approve a load factor for pedestrian loads of not less than that required by AS/NZS 1170.1.

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TABLE 7.3

LOAD FACTORS FOR DESIGN PEDESTRIAN

AND SERVICE LIVE LOADS

Limit state Load


Pedestrian load 1.8 1.0

Service live loads 2.0 1.0

8 RAILWAY TRAFFIC

8.1 General

Railway bridges shall be designed for the loads specified in Clause 8, unless specified

otherwise by the rail authority. Bridges carrying light rail, cane railways and the like shall

be designed for loads specified by the relevant authority.

8.2 300LA railway traffic load

The 300LA load shall consist of groups of vehicles with four axles each having a load of

300 kN, and have axle spacings of 1.7 m, 1.1 m and 1.7 m. To simulate coupled

locomotives, a 360 kN axle load shall be added 2 m in front of the axle group, as shown in

Figure 8.2(A). The spacing between the centres of each vehicle axle group shall vary

between 12 m and 20 m to give maximum effect in the member under consideration, as

shown in Figure 8.2(B).

The position of the loads and the number of axle groups shall be selected so as to give

maximum load effects in the member under consideration.

FIGURE 8.2(A) 300LA RAILWAY TRAFFIC LOADSAXLE LOADS

FIGURE 8.2(B) 300LA RAILWAY TRAFFIC LOADSAXLE GROUP SPACINGS

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8.3 Multiple track factor for railway bridges

When loading a number of tracks simultaneously, the multiple track factors given in

Table 8.3 shall be used, as appropriate. These factors shall be applied to the total railway

traffic loads, depending on the number of loaded tracks being considered.

The selection of the number of tracks to be loaded with railway traffic loads shall be such

as to give the greatest live load effects in the member under consideration.

TABLE 8.3

MULTIPLE TRACK FACTORS

Number of tracks loaded Multiple track factor

1 1.00

2 1.00

3 0.85

4 0.70

5 or more 0.60

8.4 Dynamic load allowance

8.4.1 General

The dynamic load allowance () for railway live load effects shall be a proportion of the

static railway live load, and shall be calculated by the methods specified in this Clause. It

shall have the same value for structures of reinforced or prestressed concrete, steel, or

composite construction. The value of shall depend upon the characteristic length (L). A

distinction is made between different methods of supporting the track, i.e., with ballast or

transom top structures.

The dynamic load allowance applies to both the ultimate and serviceability limit states. The

design action is equal to (1 + ) the load factor the action under consideration.

In cases where a member acts in two different modes, e.g., as a deck support and also as

part of the main girder, the dynamic load allowance shall be calculated separately for the

structural actions in each mode, and the actions summed.

8.4.2 Characteristic length (L)

For main girders and components of railway bridge superstructures, the characteristic

length (L) for each component shall be dependent on the structural geometry. The values

of L for superstructure elements shall be as given in Table 8.4.2.

For bridge bearings and abutments, L shall be the length of the supported span.

For intermediate piers, L shall be the sum of the lengths of the adjacent spans.

For bearings supporting floor members, L shall be as given in Table 8.4.2.

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TABLE 8.4.2

CHARACTERISTIC LENGTH (L)

Case

No. Bridge members, types of bridge

Characteristic length (L)

m

Floor members

1 Stringers Cross-girder spacing +3.0

2 End stringers Cross-girder spacing

3 Cantilevered stringers 0.5

4 Cross-girders, including cantilevered cross-

girders, loaded by simply supported stringers

and continuous deck elements

Twice the cross-girder spacing +3.0

5 End cross-girders, including cantilevered end

cross-girders 4.0

6 Deck slabs between supports Span of the main girders or twice the span of the

deck slab, whichever is less

7 Cantilevered deck slabs Span of the main girders or twice the distance

between each support, whichever is less

8 Suspension bars or supports loaded by cross-

girders only

The values to be used shall correspond to those

applying to the cross-girder, as given in Cases 4

and 5

Main girders

9 Simply supported main girders Span of main girders

Continuous main girders over n spans where for

Lm = 1/n (L1 + L2+Ln) n = 2 3 4 5

x = 1.2 1.3 1.4 1.5

10

L = xLm, but Lmax.

11 Cantilever portions of cantilever bridges Length of the cantilevered portion plus the span of

any suspended girder supported by the cantilever

12 Suspended girders of suspended span bridges Span of the suspended girder

13 Arches Half span

14 Plate web girders at bottom of welded stiffeners 0.5

15 Truss members:

(a) Top and bottom chords Three times the length from adjacent panel points

(b) Verticals Three times the length between chords

(c) Diagonals not intersected by members

complying with this Standard

Three times the horizontal or vertical projection,

whichever is the shorter

(d) Diagonals intersected by members


Six times the horizontal or vertical projection of the

overall length, whichever is the shorter

Lattice girder members:

(a) Top and bottom flanges and webs As for main girders

16

(b) Lattice members Six times the horizontal or vertical projection of the

overall length from web to web, whichever is the

shorter

(continued)

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TABLE 8.4.2 (continued)

Case

No. Bridge members, types of bridge


m

Bracing members:

(a) Horizontal or vertical members parallel to

or perpendicular to the track

Three times the member length

(b) Diagonal members with respect to Item (a),

if not intersected by members complying

with this Standard

Three times the projected length horizontally or

vertically, parallel to or perpendicular to the track,

whichever is the shorter

17

(c) Diagonal members, with respect to

Item (a), if intersected by members


Six times the projected overall length horizontally

or vertically, parallel to or perpendicular to the

track, whichever is the shorter

where

n = number of continuous main girder spans

L1, L2, Ln = span lengths of a continuous structure, in metres

Lmax. = largest of the values L1, L2, Ln, in metres

8.4.3 Dynamic load allowance for bending effects

8.4.3.1 Ballasted deck spans

The value of the dynamic load allowance () for bending moment for ballasted deck spans

shall be as given in Table 8.4.3.1.

TABLE 8.4.3.1

VALUES OF FOR BENDING MOMENT

FOR BALLASTED DECK SPAN


m Dynamic load allowance ()

3.6 1.0

>3.6 0.27 0.20

2.16

0.5

L

NOTE: The value of shall not be less than 0.

8.4.3.2 Open deck spans and spans with direct rail fixation

The value of the dynamic load allowance () for bending moment for open deck spans or

spans with direct rail fixation shall be as given in Table 8.4.3.2.

TABLE 8.4.3.2

VALUES OF FOR BENDING MOMENT

FOR OPEN DECK SPANS AND SPANS

WITH DIRECT RAIL FIXATION


m Dynamic load allowance ()

2.0 1.6

> 2.0 17.020.0

16.2

0.5

L

NOTE: The value of shall not be less than 0.

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8.4.4 Application

For all parts of the structure extending down to the ground level, the dynamic load

allowance () shall be as specified in Clauses 8.4.3.

For culverts and soil steel structures below the ground level, shall be linearly transitioned

from the ground level value to zero at a cover depth of 2 m. For structures in embankments,

the ground level shall be taken as the underside of the ballast.

The dynamic load allowance established for the appropriate cover depth shall apply to the

entire structure. The depth of the cover shall be measured from the underside of the ballast.

8.4.5 Dynamic load allowance for other load effects

The dynamic load allowance () for shear, torsion and reactions shall be taken as 2/3 of the

value for bending moment.

Where the application of the dynamic load allowance leads to greater safety or stability,

e.g., against overturning, shall be taken as 0.

Where deflections are to be calculated for serviceability loads, including dynamic load

allowance, 2/3 of the dynamic load allowance shall be used.

8.4.6 Dynamic load reversal

Consideration shall be given to the reversal of the dynamic response to live load. Vibrations

may continue and slowly decay after passing of traffic. The frequency and rate of strain in

dynamic load reversal are critical in fatigue damage accumulation. In particular, the

minimum reaction on bearings shall permit for the reduction, which may occur from the

results of the dynamic effects.

8.4.7 Application to dedicated lines and traffic

Where detailed information is available for specific structures and track standard, and

where train speeds are known, may be determined as required by the authority.

NOTE: A procedure for the determination of is described in AS 5100.2 Supp 1.

8.5 Distribution of railway traffic load

8.5.1 General

The distribution of railway live load to the supporting members shall be calculated using a

rigorous analysis in accordance with the appropriate clauses of the relevant material Section

of the Standard.

In the absence of a rigorous analysis, railway traffic loads shall be distributed as set out in

Clauses 8.5.2 to 8.5.5, as appropriate.

8.5.2 Open deck steel railway bridges

Timber bridge transoms shall be designed on the assumption that the maximum wheel load

on each rail shall be distributed equally to all transoms or fractions thereof within a length

of 1.2 m, but shall not be greater than three transoms, and the load shall be applied with a

dynamic load allowance of 1.0.

For the design of beams, the live load shall be distributed and shall be applied via the

transoms as above. In such cases, additional longitudinal distribution of such loads shall not

be assumed, and the full dynamic load allowance shall be applied to the beams.

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8.5.3 Ballasted deck steel railway bridges

Provided that sleepers are spaced at no more than 700 mm centres, and not less than

150 mm of ballast is provided under them, the load from each axle may be uniformly

distributed longitudinally over a length of 1.1 m, and uniformly distributed laterally over a

width equal to the length of the sleeper plus the minimum distance from the bottom of

sleeper to the top of the beams. This width shall be not greater than 4.0 m, the distance

between track centres of multiple track bridges, or the width of the deck between ballast

retainers.

8.5.4 Ballasted deck concrete railway bridges

Railway traffic loads on ballasted deck railway bridges shall be uniformly distributed

longitudinally over a length of 1 m, plus the depth of ballast under the sleeper, plus twice

the effective depth of slab. The total length shall be not greater than the axle spacing.

The loads shall be uniformly distributed laterally over a width equal to the length of the

sleepers plus the depth of ballast below the bottom of the sleepers, plus twice the effective

depth of the concrete slab, unless limited by the extent of the structure. This width shall not

be greater than the distance between centres of adjacent tracks on multiple track railway

bridges.

8.5.5 Direct fixation

The distribution of rail wheel loads through directly fixed track shall be determined on the

basis of the relative stiffness of the rail, the rail fixing supports and the superstructure.

For the determination of the rail wheel load forces, the dynamic load allowance () shall be

based on a value of L equal to the longitudinal distance between centre-lines of the rail

track supports.

8.6 Horizontal forces

8.6.1 Centrifugal forces

For railway bridges on horizontal curves, allowance shall be made for the centrifugal

effects of railway traffic load by applying a centrifugal force (HCF) corresponding to each

axle load horizontally through a point 2 m above the top of the rail.

The horizontal centrifugal force shall be proportional to the design railway traffic load, and

for each axle, HCF, in kilonewtons, shall be calculated as follows:

r

AVH

2

CF

0.0077= . . . 8.6.1

where

V = design speed, in kilometres per hour

A = axle load, in kilonewtons

r = radius of curve, in metres

The specified centrifugal force shall not be increased by the dynamic load allowance.

8.6.2 Braking and traction forces

Railway bridges shall be designed for the forces arising from braking and traction forces

applied to the top of the rails. They shall be proportional to the specified railway traffic

load and, for 300LA load, shall have the values given in Table 8.6.2.

The specified longitudinal force shall not be increased by the dynamic load allowance.

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TABLE 8.6.2

BRAKING AND TRACTION FORCES

FOR 300LA LOAD

Track type Loaded length (L)

m

Horizontal force

kN

Discontinuous All 200 + 20L

L < 50 m 100 Continuous

L > 50 m 100 + 15(L 50)

For continuous track, the loaded length shall be taken to be the full length of the bridge.

The total longitudinal load on the bridge, as calculated from Table 8.6.2, shall be

distributed to the supports in proportion to their stiffnesses.

For bridges with discontinuous track, the loaded length shall be taken as the length between

the discontinuity and an abutment, or as the length between discontinuities. The

longitudinal load shall be distributed to the supports under the loaded length, in proportion

to their stiffnesses.

Continuous tracks, for the purpose of determining the longitudinal forces specified in this

Clause, shall be those tracks that have no rail discontinuities either on the bridge or within

20 m of either end of the bridge.

Where a structure or element carries two tracks, both tracks shall be considered as being

occupied simultaneously. Loads in either direction shall be applied simultaneous to both

tracks.

Where elements carry more than two tracks, longitudinal loads shall be applied

simultaneously to two tracks only.

8.6.3 Nosing loads

Railway bridges that are intended to carry 300LA traffic loads shall be designed to resist a

lateral nosing load of 100 kN applied at top of rail level in either direction and at any point

along the structure. This load shall be adjusted in proportion to the actual design traffic

load. Nosing loads shall not be increased by the dynamic load allowance. Nosing loads are

independent from the speed and shall not be reduced at low speeds.

8.7 Fatigue load

8.7.1 Fatigue design traffic load

The fatigue design traffic load for railway bridges shall be the design railway traffic load

and half of the design dynamic load allowance, with a load factor of 1.0. The distance

between the centre of the axle groups (Lv) shall be varied between 12 m and 20 m to

produce the maximum fatigue design stress range (f*) (see Clause 8.7.3).

8.7.2 Fatigue design stress range (f*

)

The fatigue design stress range (f*) in any element of a bridge structure, shall be derived

from the passage of the fatigue design traffic load over the bridge. It shall be the algebraic

difference between the maximum and minimum stresses caused by that load.

Stresses and stress ranges caused by other load effects need not be included.

8.7.3 Effective number of stress cycles (n)

The effective number of cycles (n) of the fatigue design stress range (f*) to be considered in

the design of the structure shall be calculated as follows:

n = CTnT . . . 8.7.3

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where

CT = base number of load cycles for the track category as given in Table 8.7.4

nT = number of equivalent stress cycles of amplitude (f*) per train, which depends

on Lf and Lv (see Table 8.7.3)

Lf = span of main girders, trusses or stringers; or

cross-girder spacing for cross-girders

Lv = distance between the centres of the axle groups (i.e., the length of the

vehicle)

TABLE 8.7.3

VALUES OF nT

Lf nT

< 2.5 240

2.5 < Lf < 9.0 60.0

9.0 < Lf < 25.0

( )

2 .Min

60 .Max

2 + 2

60

f

fv

3

L

LL

> 25.0 2.0

8.7.4 Track category for fatigue load

The base number of load cycles (CT) for fatigue load depends on the track category and

shall be as given in Table 8.7.4.

TABLE 8.7.4

VALUES OF CT

Track category CT

Heavy haul 6 105

Main line freight 1 105

Branch line 1 104

8.7.5 Multiple track bridges

For elements of multiple track railway bridges that are subject to loads from more than one

track, the fatigue loads, both the fatigue design traffic load specified in Clause 8.7.1 and the

fatigue design stress range specified in Clause 8.7.2, shall be determined from the full

fatigue design traffic load on one track, and a load on the other track(s) of 80% of their full

fatigue design traffic load with no dynamic load allowance.

NOTE: A more accurate calculation may be carried out by estimating the number of load events

in the life of the element in which two or more trains will be loading the element under

consideration at any one time. If the effect of the load from multiple tracks results in a stress

range more severe than that due to a single track, a cumulative damage calculation for the cases

of single-track and multiple-track loads should be performed.

8.8 Load factors

For ultimate and serviceability limit state design loads, the load factors for the design

railway traffic load shall be as given in Table 8.8(A).

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TABLE 8.8(A)

LOAD FACTORS FOR

DESIGN RAILWAY TRAFFIC LOADS

Limit state Loads


300LA railway traffic load 1.6 1.0

The load factors to be applied in calculating centrifugal, nosing and longitudinal forces

shall be as given in Table 8.8(B).

TABLE 8.8(B)

LOAD FACTORS FOR

DESIGN RAILWAY TRAFFIC LOADS

Limit state Traffic load


Centrifugal forces 1.6 1.0

Nosing forces 1.6 1.0

Longitudinal braking and traction forces 1.6 1.0

Each of the design horizontal forces due to railway load shall be applied simultaneously

with the vertical railway load and such load cases shall be considered a single load, as

specified in Clause 22.1.3.

Centrifugal forces and nosing loads shall not be applied simultaneously.

8.9 Deflection limits

The deflection limits of a railway bridge under traffic for serviceability limit state shall be

appropriate to the structure and its intended use, the nature of the loading and the elements

supported by it.

Notwithstanding this requirement, the deflection of railway bridges for serviceability limit

state under live load plus dynamic load allowance shall be not greater than 1/640 of the

span and 1/320 of the cantilever projection.

NOTE: In order not to detract from their appearance, bridges should be designed so that their hog

does not exceed 1/300 of the span and they do not sag under permanent loads.

Railway bridges shall not deflect so that they infringe clearance diagrams.

9 MINIMUM LATERAL RESTRAINT CAPACITY

To ensure that the superstructure has sufficient lateral restraint to resist lateral forces not

otherwise accounted for in the design, a positive lateral restraint system between the

superstructure and the substructure shall be provided at piers and abutments.

For continuous superstructures, lateral restraints may be omitted at some piers provided

each continuous section of the superstructure between expansion joints is adequately

restrained.

The restraint system for each continuous section of the superstructure shall be capable of

resisting an ultimate design horizontal force normal to the bridge centre-line of 500 kN or

5% of the superstructure dead load at that support, whichever is greater. Supports providing

this lateral restraint shall also be designed to resist this design force. A load factor of 1.0

shall be used.

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Restraints shall have sufficient lateral clearance to allow thermal movements, especially on

wide and curved superstructures.

If the transverse load requirement specified in other Parts of AS 5100 is greater than the

requirements of this Clause, then the restraints may be deemed to satisfy the requirements

of this Clause.

10 COLLISION LOADS

10.1 General

Collision protection shall be considered in accordance with AS 5100.1. The design collision

loads shall be as specified in Clauses 10.2 to 10.4, where applicable.

10.2 Collision load from road traffic

Where the supports for a road bridge or a railway bridge are not located behind appropriate

protective traffic barriers, they shall be designed to resist a minimum equivalent static load

of 2000 kN applied at an angle of 10 from the direction of the road centre-line passing

under the bridge. The load shall be applied 1.2 m above ground level. This load, in

conjunction with the ultimate design dead loads on the structure, shall be considered at

ultimate limit states, with a load factor of 1.0.

10.3 Loads on protection beams

Where required by the relevant authority, protection beams shall be installed to protect the

superstructure of low clearance bridges from impact from road vehicles. They shall be

designed for the ultimate loads given in Table 10.3, with a load factor of 1.0.

TABLE 10.3

ULTIMATE LOADS ON PROTECTION BEAMS

Loads Ultimate limit state

kN

1000 (towards the bridge) Horizontal loads

750 (away from the bridge)

Vertical load (uplift) 500

Protection beam supports shall be capable of resisting loads 25% greater than the capacity

of the protection beam itself.

10.4 Collision load from rail traffic

10.4.1 General

This Clause applies to all structures above the railway track including railway bridges over

other railways, overbridges, pedestrian bridges, air space developments, developments

adjacent to railways and similar structures in underground railways.

This Clause does not apply to

(a) structures that only support signals, overhead wiring, lighting or communications

equipment;

(b) gang sheds adjacent to tracks; or

(c) waiting rooms and ticket offices on platforms.

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10.4.2 Provision of alternative load path

Where an alternative load path is to be provided, the superstructure shall be designed with

sufficient redundancy to be capable of supporting the deck load plus 20% of the live load at

the ultimate limit state with one or more piers or columns removed. The number of supports

to be removed shall be determined by a risk analysis approved by the relevant rail authority.

In the case of railway bridges over other railways and where determined by the relevant rail

authority, the live load for the redundancy action shall be increased from 20% to 60%.

10.4.3 Collision loads on support elements

Unless specified otherwise by the rail authority, supports for bridges and structures located

within 10 m of the centre-line of the railway track, not complying with the redundancy

requirements of Clause 10.4.2, shall be designed to resist the following minimum collision

loads applied simultaneously as an ultimate design load with a load factor of 1.0:

(a) 3000 kN parallel to rails.

(b) 1500 kN normal to rails.

The loads specified in Items (a) and (b) shall be applied horizontally, 2 m above rail level

and shall be applied in conjunction with the ultimate design dead loads on the structure.

Where supporting elements are located between 10 m and 20 m from the centre-line of the

railway track, a risk analysis shall be carried out by the relevant rail authority, which shall

determine the required level of protection. If the level of redundancy does not meet the

requirements of Clause 10.4.2, the piers and columns shall be designed to resist a minimum

collision load applied as an ultimate load of 1500 kN, at any angle in the horizontal plane,

2 m above the rail level.

NOTE: Some rail authorities permit relaxation of this loading where platforms, under certain

conditions, provide protection to the columns.

10.4.4 Bridge and structural components within 10 m of the centre-line of the railway

track

Any part of any structure specified in Clause 10.4.1, including the superstructure, within

10 m horizontally and 5 m vertically of the centre-line of the nearest railway track, shall be

designed for a 500 kN minimum collision load applied as an ultimate design load. The

collision load shall be applied in any direction. Above 5 m and up to 10 m vertically above

the railway track level, this collision load shall vary linearly from 500 kN at 5 m to zero at

10 m. When applied vertically upwards, the force shall be distributed over an area of one

square metre, to allow for roof crushing of the railway vehicle.

The 500 kN force may act in conjunction with the ultimate design dead load and either

(a) +1.0 DLg

collision load ................................................(min. g

shall be used); or

(b) ++ 1.0 LL0.4 DL LLg collision load ................................. (max. g shall be used);

whichever gives the worst case. Relaxation of the 500 kN collision load on supporting

members complying with the redundancy provisions of Clause 10.4.2 is permitted, but not

for members of the superstructure.

Platforms shall not be assumed to provide a degree of protection to permit reduction of the

500 kN collision load.

The 500 kN collision load shall not be applied in conjunction with the loads specified in

Clause 10.4.3.

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10.4.5 Underground railway, air space developments and similar situations

For all underground railways and air space developments, except on platforms, the 500 kN

collision load specified in Clause 10.4.4 shall be increased to 1500 kN. When applied

vertically upwards, this 1500 kN collision force shall be distributed over an area of 2 m2.

10.4.6 Other design requirements

In addition to the design requirements specified herein, any other design requirements of

the relevant rail authority shall be satisfied.

The loads specified herein shall also be applied to deflection walls.

A load factor of 1.0 for the ultimate limit state shall be used.

Piers and columns shall be designed for the same load combinations specified in

Clause 10.4.4.

10.5 Derailment loads

10.5.1 General

Railway bridges designed to carry 300LA loads shall be designed for two separate train

derailment load cases as set out in Clauses 10.5.2 and 10.5.3. The loads shall be

proportioned if a different live load is specified. Derailment loads shall only be considered

for the ultimate limit state without dynamic load allowance, and shall act in combination

with long-term permanent effects.

10.5.2 Derailment load Case A

In derailment load Case A, a bridge shall be designed for the more unfavourable of the

following loads:

(a) 300LA load applied as wheel loads, separated by the track gauge, parallel to the track,

and in the most unfavourable position within a distance GB of track centre-line.

(b) A single point load of 200 kN, acting in the most unfavourable position within a

distance GB of the track centre-line;

where GB is equal to 1.5 times the railway gauge.

For the loads specified in Items (a) and (b), an ultimate load factor of 1.2 shall be used.

10.5.3 Derailment load Case B

In derailment load Case B, a bridge shall be designed for an equivalent line load of

100 kN/m, over a length of up to 20 m, acting on the edge of the superstructure, using an

ultimate load factor of 1.0.

11 KERB AND BARRIER DESIGN LOADS AND OTHER REQUIREMENTS FOR

ROAD TRAFFIC BRIDGES

11.1 Kerb design loads

Kerbs shall be designed to resist an ultimate design load of 15 kN per metre applied

laterally at the top of the kerb.

11.2 Barriers

11.2.1 General

The design criteria, including loads and geometric requirements, provided in this Clause 11

and in AS 5100.1, shall be used for the following:

(a) Developing a prototype barrier for a crash test program to validate vehicle/barrier

interaction performance.

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(b) Designing minor modifications to a barrier system which has been validated by either

crash testing or performance review to develop a geometrically and structurally

5100.2-2004

Documents

council of standards

copyright standards

smec australia

australia isbn

standards australia

australian bridge design

design loads

current standard