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STAAD.Pro

STructuralAnalysis

AndDesign

Program


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GENERAL DESCRIPTION

The STAAD.Pro Graphical User Interface (GUI) is normally used to create all input specifications

and all output reports and displays (See the Graphical Environment manual). These structural modeling

and analysis input specifications are stored in a text file with extension .STD. When the GUI does a File

Open to start a session with an existing model, it gets all of its information from the STD file. A user mayedit/create this STD file and have the GUI and the analysis engine both reflect the changes.

The STD file is processed by the STAAD analysis engine to produce results that are stored in several

files with extensions such as ANL, BMD, TMH, etc. The ANL text file contains the printable output as

created by the specifications in this manual. The other files contain the results (displacements,

member/element forces, mode shapes, section forces/moments/displacements, etc.) that are used by

the GUI in post processing mode.

Input Generation

The GUI (or user) communicates with the STAAD analysis engine through the STD input file. That inputfile is a text file consisting of a series of commands which are executed sequentially. The commands

contain either instructions or data pertaining to analysis and/or design.

Types of Structures

A STRUCTURE can be defined as an assemblage of elements. STAAD is capable of analyzing and

designing structures consisting of bothframe, plate/shell and solid elements. Almost any type of

structure can be analyzed by STAAD.

A SPACE structure, which is a three dimensional framed structure with loads applied in any plane, is the

most general.

A PLANE structure is bound by a global X-Y coordinate system with loads in the same plane.

A TRUSS structure consists of truss members which can have only axial member forces and no bending

in the members.

A FLOOR structure is a two or three dimensional structure having no horizontal (global X or Z)

movement of the structure [FX, FZ & MY are restrained at every joint]. The floor framing (in global X-Z

plane) of a building is an ideal example of a FLOOR structure. Columns can also be modeled with the

floor in a FLOOR structure as long as the structure has no horizontal loading. If there is any horizontal

load, it must be analyzed as a SPACE structure.

Specification of the correct structure type reduces the number of equations to be solved during the

analysis. This results in a faster and more economic solution for the user.

Unit Systems

The user is allowed to input data and request output in almost all commonly used engineering unit

systems including MKS, SI and FPS. In the input file, the user may change units as many times as


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required. Mix and match between length and force units from different unit systems is also allowed. The

input-unit for angles (or rotations) is degrees. However, in JOINT DISPLACEMENT output, the rotations

are provided in radians. For all output, the units are clearly specified by the program.

Structure Geometry and Coordinate Systems

A structure is an assembly of individual components such as beams, columns, slabs, plates etc.. In

STAAD, frame elements and plate elements may be used to model the structural components. Typically,

modeling of the structure geometry consists of two steps:

A. Identification and description of joints or nodes.

B. Modeling of members or elements through specification of connectivity (incidences) between joints.

In general, the term MEMBER will be used to refer to frame elements and the term ELEMENT will be

used to refer to plate/shell and solid elements. Connectivity for MEMBERs may be provided through the

MEMBER INCIDENCE command while connectivity for ELEMENTs may be provided through the ELEMENT

INCIDENCE command.

STAAD uses two types of coordinate systems to define the structure geometry and loading patterns. The

GLOBAL coordinate system is an arbitrary coordinate system in space which is utilized to specify the

overall geometry & loading pattern of the structure. A LOCAL coordinate system is associated with each

member (or element) and is utilized in MEMBER END FORCE output or local load specification. For input,

refer the 'Related Topics' below.

Global Coordinate System

The following coordinate systems are available for specification of the structure geometry.

1. Conventional Cartesian Coordinate System: This coordinate system (Fig. 1.2) is a rectangularcoordinate system (X, Y, Z) which follows the orthogonal right hand rule. This coordinate system

may be used to define the joint locations and loading directions. The translational degrees of

freedom are denoted by u1, u2, u3 and the rotational degrees of freedom are denoted by u4, u5

& u6.

2. Cylindrical Coordinate System: In this coordinate system, (Fig. 1.3) the X and Y coordinates ofthe conventional cartesian system are replaced by R (radius) and (angle in degrees). The Z

coordinate is identical to the Z coordinate of the cartesian system and its positive direction is

determined by the right hand rule.

3. Reverse Cylindrical Coordinate System: This is a cylindrical type coordinate system (Fig. 1.4)where the R- plane corresponds to the X-Z plane of the cartesian system. The right hand ruleis followed to determine the positive direction of the Y axis.


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Local Coordinate System

A local coordinate system is associated with each member. Each axis of the local orthogonal coordinate

system is also based on the right hand rule. Fig. 1.5 shows a beam member with start joint 'i' and end

joint 'j'. The positive direction of the local x-axis is determined by joining 'i' to 'j' and projecting it in the

same direction. The right hand rule may be applied to obtain the positive directions of the local y and z

axes. The local y and z-axes coincide with the axes of the two principal moments of inertia. Note that the

local coordinate system is always rectangular.

A wide range of cross-sectional shapes may be specified for analysis. These include rolled steel shapes,

user specified prismatic shapes etc..

Loads

Loads in a structure can be specified as joint load, member load, temperature load and fixed-end

member load. STAAD can also generate the self-weight of the structure and use it as uniformly

distributed member loads in analysis. Any fraction of this self-weight can also be applied in any desired

direction.

Joint Load

Joint loads, both forces and moments, may be applied to any free joint of a structure. These loads act in

the global coordinate system of the structure. Positive forces act in the positive coordinate directions.

Any number of loads may be applied on a single joint, in which case the loads will be additive on that

joint.

Member Load

Three types of member loads may be applied directly to a member of a structure. These loads areuniformly distributed loads, concentrated loads, and linearly varying loads (including trapezoidal).

Uniform loads act on the full or partial length of a member. Concentrated loads act at any intermediate,

specified point. Linearly varying loads act over the full length of a member. Trapezoidal linearly varying

loads act over the full or partial length of a member. Trapezoidal loads are converted into a uniform load

and several concentrated loads.

Area / Oneway Load / Floor Load

Often a floor is subjected to a uniform pressure. It could require a lot of work to calculate the equivalent

member load for individual members in that floor. However, with the AREA, ONEWAY or FLOOR LOAD

facilities, the user can specify the pressure (load per unit square area). The program will calculate thetributary area for these members and calculate the appropriate member loads. The Area Load and

Oneway load are used for one way distribution and the Floor Load is used for two way distribution.

The following assumptions are made while transferring the area/floor load to member load:

a) The member load is assumed to be a linearly varying load for which the start and the end values may

be of different magnitude.


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b) Tributary area of a member with an area load is calculated based on half the spacing to the nearest

approximately parallel members on both sides. If the spacing is more than or equal to the length of the

member, the area load will be ignored.

c) Area/Floor load should not be specified on members declared as MEMBER CABLE, MEMBER TRUSS,

MEMBER TENSION or MEMBER COMPRESSION or CURVED.

Fixed End Member Load

Load effects on a member may also be specified in terms of its fixed end loads. These loads are given in

terms of the member coordinate system and the directions are opposite to the actual load on the

member. Each end of a member can have six forces: axial; shear y; shear z; torsion; moment y, and

moment z.

Prestress and Poststress Member Load

Members in a structure may be subjected to prestress load for which the load distribution in the

structure may be investigated. The prestressing load in a member may be applied axially or eccentrically.

The eccentricities can be provided at the start joint, at the middle, and at the end joint. These

eccentricities are only in the local y-axis. A positive eccentricity will be in the positive local y-direction.

Since eccentricities are only provided in the local y-axis, care should be taken when providing prismatic

properties or in specifying the correct BETA angle when rotating the member coordinates, if necessary.

Two types of prestress load specification are available; PRESTRESS, where the effects of the load are

transmitted to the rest of the structure, and POSTSTRESS, where the effects of the load are experienced

exclusively by the members on which it is applied.

Temperature and Strain Load

Temperature difference through the length of a member as well as differences of both faces ofmembers and elements may also be specified. The program calculates the axial strain (elongation and

shrinkage) due to the temperature difference. From this it calculates the induced forces in the member

and the analysis is done accordingly. The strain intervals of elongation and shrinkage can be input

directly.

Support Displacement Load

Static Loads can be applied to the structure in terms of the displacement of the supports. Displacement

can be translational or rotational. Translational displacements are provided in the specified length while

the rotational displacements are always in degrees. Note that displacements can be specified only in

directions in which the support has an "enforced" specification in the Support command.


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NOMENCLATURE OF STEEL SECTIONS

BEAM SECTIONS: Following nomenclature is followed for steel beam sections in India:

(1) ISJB: Indian standard junior beams(2) ISLB: Indian standard light weight beams(3) ISMB: Indian standard medium weight beams(4) ISWB: Indian standard wide flange beams(5) ISHB: Indian standard heavy weight beams

Beams will be designated by Type Web x Flange size (E.g ISMB 600x210)

PARALLEL FLANGE BEAMS:

(1) NPB: Indian national narrow parallel flange beams(2) WPB: Indian national wide parallel flange beams(3) UB: Universal beams(4) UC: Universal columns

Parallel beams will be designated by Type Web size x Flange size x Unit weight (E.g UB

610x229x125)

ANGLES:

(1) ISA: Indian standard equal angle(2) ISUA: Indian standard unequal angle

Angles will be designated by Type Face1 size x Face2 size x Thickness (E.g ISA 100x100x6)

CHANNELS:

(1) ISJC: Indian standard junior channel(2) ISLC: Indian standard light weight channel(3) ISMC: Indian standard medium weight channel

Channel will be designated by Type Web size x Flange size (E.g ISMC 100x50)

RAILS:

(1) ISCR: Indian standard crane rail(2) ISHR: Indian standard heavy rail

Rails will be designated by Type Head size (E.g ISCR 100)

PLATES:

Plates will be designated by thickness.


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FLATS:

Flats will be designated by Width x Thickness (E.g Flat 100x6)

ROUND BAR:

(1) ISRO: Indian standard roundRound bar will be designated by Diameter (E.g ISRO 50)

HEXAGON BAR:

Hexagon bar will be designated by one side (E.g Hex. Bar 50)

SQUARE BAR:

Square bar will be designated by one side size (E.g Sq. Bar 100)

SQUARE HOLLOW BAR:

Square hollow bar will be designated by Sq. Bar Face1 size x Face2 size x Thickness (E.g Sq. Bar

50x50x2)

RECTANGULAR HOLLOW SECTION:

Rectangular hollow bar will be designated by Rect. Bar Face1 size x Face size2 x Thickness (E.g

Rect. Sq. Bar 100x50x2).


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STEEL DESIGN PER IS800

STAAD contains a broad set of facilities for designing structural members as individual components of an

analyzed structure. The member design facilities provide the user with the ability to carry out a number

of different design operations. These facilities may be used selectively in accordance with the

requirements of the design problem. The operations to perform a design are:

Specify the members and the load cases to be considered in the design. Specify whether to perform code checking or member selection. Specify design parameter values, if different from the default values. Specify whether to perform member selection by optimization.

These operations may be repeated by the user any number of times depending upon the design

requirements. The entire ISI steel section table is supported. Section 8B.13 describes the specification of

steel sections.

Allowable Stresses

The member design and code checking in STAAD are based upon the allowable stress design method as

per IS:800 (1984). It is a method for proportioning structural members using design loads and forces,

allowable stresses, and design limitations for the appropriate material under service conditions. It would

not be possible to describe every aspect of IS:800 in this manual. This section, however, will discuss the

salient features of the allowable stresses specified by IS:800 and implemented in STAAD. Appropriate

sections of IS:800 will be referenced during the discussion of various types of allowable stresses.

Design Parameters

In STAAD implementation of IS:800, the user is allowed complete control of the design process through

the use of design parameters. Available design parameters to be used in conjunction with IS:800 are

listed in Table 7B.1 of this section along with their default values and applicable restrictions. Users

should note that when the TRACK parameter is set to 1.0 and use in conjunction with this code,

allowable bending stresses in compression (FCY & FCZ), tension (FTY & FTZ), and allowable shear stress

(FV) will be printed out in Member Selection and Code Check output in Mpa. When TRACK is set to 2.0,

detailed design output will be provided.

Stability Requirements

Slenderness ratios are calculated for all members and checked against the appropriate maximum values.

Section 3.7 of IS:800 summarizes the maximum slenderness ratios for different types of members. In

STAAD implementation of IS:800, appropriate maximum slenderness ratio can be provided for each

member. If no maximum slenderness ratio is provided, compression members will be checked against a

maximum value of 180 and tension members will be checked against a maximum value of 400.


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Truss Members

As mentioned earlier, a truss member is capable of carrying only axial forces. So in design no time is

wasted in calculating bending or shear stresses, thus reducing design time considerably. Therefore, if

there is any truss member in an analysis (like bracing or strut, etc.), it is wise to declare it as a truss

member rather than as a regular frame member with both ends pinned.

Deflection Check

This facility allows the user to consider deflection as a criteria in theCODE CHECKandMEMBER

SELECTIONprocesses. The deflection check may be controlled using three parameters which are

described in Table 7B.1. Note that deflection is used in addition to other strength and stability related

criteria. The local deflection calculation is based on the latest analysis results.

Code Checking

The purpose of code checking is to verify whether the specified section is capable of satisfying applicable

design code requirements. The code checking is based on the IS:800 (1984) requirements. Forces and

moments at specified sections of the members are utilized for the code checking calculations. Sections

may be specified using the BEAM parameter or the SECTION command. If no sections are specified, the

code checking is based on forces and moments at the member ends.

The code checking output labels the members as PASSed or FAILed. In addition, the critical condition

(applicable IS:800 clause no.), governing load case, location (distance from the start) and magnitudes of

the governing forces and moments are also printed out.

Member Selection

STAAD is capable of performing design operations on specified members. Once an analysis has beenperformed, the program can select the most economical section, that is the lightest section, which

satisfies the applicable code requirements. The section selected will be of the same type (I-Section,

Channel etc.) as originally specified by the user. Member selection may be performed with all types of

steel sections listed in Section 7B.13 and user provided tables. Selection of members, whose properties

are originally provided from user specified table, will be limited to sections in the user provided table.

Member selection can not be performed on members whose cross sectional properties are specified as

PRISMATIC.

The process of MEMBER SELECTION may be controlled using the parameters listed in Table 8B.1. It may

be noted that the parameters DMAX and DMIN may be used to specify member depth constraints for

selection. If PROFILE parameter is provided, the search for the lightest section is restricted to thatprofile. Up to three (3) profiles may be provided for any member with a section being selected from

each one.

Member Selection By Optimization

Steel section selection of the entire structure may be optimized. The optimization method utilizes a

state-of-the -art numerical technique which requires automatic multiple analysis. The user may start


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without a specifically designated section. However, the section profile type (BEAM, COLUMN, CHANNEL,

ANGLE etc.) must be specified using the ASSIGN command (see Chapter 6). The optimization is based on

member stiffness contributions and corresponding force distributions. An optimum member size is

determined through successive analysis/design iterations. This method requires substantial computer

time and hence should be used with caution.

Tabulated Results of Steel Design

For code checking or member selection, the program produces the result in a tabulated fashion. The

items in the output table are explained as follows:

a) MEMBER refers to the member number for which the design is performed.

b) TABLE refers to the INDIAN steel section name which has been checked against the steel code or has

been selected.

c) RESULT prints whether the member has PASSED or FAILed. If the RESULT is FAIL, there will be an

asterisk (*) mark in front of the member number.

d) CRITICAL COND refers to the section of the IS:800 code which governs the design.

e) RATIO prints the ratio of the actual stresses to allowable stresses for the critical condition. Normally a

value of 1.0 or less will mean the member has passed.

f) LOADING provides the load case number which governs the design.

g) FX, MY and MZ provide the axial force, moment in local y-axis and moment in local z-axis respectively.

Although STAAD does consider all the member forces and moments (except torsion) to perform design,

only FX, MY and MZ are printed since they are the ones which are of interest, in most cases.

h) LOCATION specifies the actual distance from the start of the member to the section where design

forces govern.

i) If the parameter TRACK is set to 1.0, the program will block out part of the table and will print

allowable bending stresses in compression (FCY & FCZ) and tension (FTY & FTZ), allowable axial stress in

compression (FA), and allowable shear stress (FV).

Indian Steel Table

This is an important feature of the program since the program will read section properties of a steelmember directly from the latest ISI steel tables (as published in ISI-800). These properties are stored in

memory corresponding to the section designation (e.g. ISMB250, etc.). If called for, the properties are

also used for member design. Since the shear areas are built in to these tables, shear deformation is

always considered for these members.

Almost all ISI steel tables are available for input. A complete listing of the sections available in the built-

in steel section library may be obtained using the tools of the graphical user interface.


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Following are the descriptions of all the types of sections available:

Rolled Steel Beams (ISJB, ISLB, ISMB and ISHB).

All rolled steel beam sections are available the way they are designated in the ISI handbook., e.g.

ISJB225, ISWB400, etc.

In case of two identical beams, the heavier beam is designated with an A on the end., e.g. ISHB400 A,

etc.

Rolled Steel Channels (ISJC, ISLCand ISMC)

All these shapes are available as listed in ISI section handbook. Designation of the channels are as per

the scheme used by ISI.

Double Channels

Back to back double channels, with or without spacing between them, are available. The letter D in front

of the section name will specify a double channel, e.g. D ISJC125, D ISMC75 etc.

Rolled Steel Angles

Both rolled steel equal angles and unequal angles are available for use in the STAAD implementation of

ISI steel tables

At present there is no standard way to define the local y and z axes for an angle section

Double Angles

Short leg back to back or long leg back to back double angles can be specified by inputting the word SD

or LD, respectively, in front of the angle size. In case of an equal angle either LD or SD will serve the

purpose.

Rolled Tees (ISHT, ISST, ISLT and ISJT)

All the rolled tee sections are available for input as they are specified in the ISI handbook.

Pipes (Circular Hollow Sections)

To designate circular hollow sections from ISI tables, use PIP followed by the numerical value ofdiameter and thickness of the section in mm omitting the decimal section of the value provided for

diameter.

Circular pipe sections can also be specified by providing the outside and inside diameters of the section.

Only code checking and no member selection will be performed if this type of specification is used.

Tubes (Rectangular or Square Hollow Sections)


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Designation of tubes from the ISI steel table is illustrated below.

Tubes, like pipes, can also be input by their dimensions (Height, Width and Thickness) and not by any

table designations.

Note that only code checking and no member selection is performed for TUBE sections specified this

way.

Plate And Angle Girders (With Flange Plates)

All plate and angle grinders (with flange plates) are available as listed in ISI section handbook. The

following example with explanations will be helpful in understanding the input procedure.


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SINGLE JOIST WITH CHANNELS AND PLATES ON THE FLANGES TO BE USED AS GIRDERS

All single joist with channel and plates on the flanges to be used as girders are available as listed in ISI

section handbook. The following example with explanations will be helpful in understanding the input

procedure.


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STEEL DESIGN PER IS802

Allowable Stresses

The member design and code checking in STAAD are based upon the allowable stress design method as

per IS:802 (1995). It is a method for proportioning structural members using design loads and forces,

allowable stresses, and design limitations for the appropriate material under service conditions.

This section discusses the salient features of the allowable stresses specified by IS:802 and implemented

in STAAD.

Stability Requirements

Slenderness ratios are calculated for all members and checked against the appropriate maximum values.

Minimum Thickness Requirement

As per Clause7.1 of IS: 802-1995 minimum thickness of different tower members shall be as follows

Code Checking

The purpose of code checking is to verify whether the specified section is capable of satisfying applicable

design code requirements. The code checking is based on the IS:802 (1995) requirements. Axial forces at

two ends of the members are utilized for the code checking calculations. The code checking output

labels the members as PASSed or FAILed. In addition, the critical condition, governing load case, location

(distance from the start) and magnitudes of the governing forces are also printed out. Using TRACK 9option calculation steps are also printed.


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Design Steps

The following are the steps followed in member design.

Step 1

Thickness of the member (maximum of web and flange thicknesses) is checked against minimum

allowable thickness, depending upon whether the member is painted or galvanised.

Step 2

If the minimum thickness criterion is fulfilled, the program determines whether the member is under

compression or tension for the loadcase under consideration. Depending upon whether the member is

under tension or compression the slenderness ratio of the member is calculated. This calculated ratio is

checked against allowable slenderness ratio.

Step 3

If the slenderness criterion is fulfilled check against allowable stress is performed. Allowable axial and

tensile stresses are calculated. If the member is under tension and there is no user defined net section

factor (NSF), the net section factor is calculated by the program itself (Refer Section 8C.10). Actual axial

stress in the member is calculated. The ratio for actual stress to allowable stress, if less than 1.0 or user

defined value, the member has passed the check.

Step 4

Number of bolts required for the critical loadcase is calculated.

Member Selection

STAAD is capable of performing design operations on specified members. Once an analysis has been

performed, the program can select the most economical section, that is the lightest section, which

satisfies the applicable code requirements. The section selected will be of the same type (either angle or

channel) as originally specified by the user. Member selection may be performed with all angle or

channel sections and user provided tables. Selection of members, whose properties are originally

provided from user specified table, will be limited to sections in the user provided table.

The process of MEMBER SELECTION may be controlled using the parameters listed in Table 8B.1. It may

be noted that the parameters DMAX and DMIN may be used to specify member depth constraints for

selection. If PROFILE parameter is provided, the search for the lightest section is restricted to thatprofile. Up to three (3) profiles may be provided for any member with a section being selected from

each one.


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Member Selection by Optimization

Steel section selection of the entire structure may be optimized. The optimization method utilizes a

state-of-the -art numerical technique which requires automatic multiple analysis. The optimization is

based on member stiffness contributions and corresponding force distributions.

An optimum member size is determined through successive analysis/design iterations. This method

requires substantial computer time and hence should be used with caution.


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CONCRETE DESIGN PER IS456

Member Dimensions

Concrete members which will be designed by the program must have certain section properties input

under the MEMBER PROPERTY command. The following example shows the required input:

will be done accordingly. In the above input, the first set of members are rectangular (450 mm depth

and 250mm width) and the second set of members, with only depth and no width provided, will be

assumed to be circular with 350 mm diameter. The third set numbers in the above example represents a

T-shape with 750 mm flange width, 200 width, 400 mm overall depth and 100 mm flange depth (See

section 6.20.2). The program will determine whether the section is rectangular, flanged or circular and

the beam or column design

Design Parameters

The program contains a number of parameters which are needed to perform design as per

IS:456(2000). Default parameter values have been selected such that they are frequently used numbers

for conventional design requirements. These values may be changed to suit the particular design being

performed. Table 8A.1 of this manual contains a complete list of the available parameters and their

default values. It is necessary to declare length and force units as Millimeter and Newtonbeforeperforming the concrete design.

Slenderness Effects And Analysis Consideration

Slenderness effects are extremely important in designing compression members. The IS:456 code

specifies two options by which the slenderness effect can be accommodated (Clause 39.7). One option is

to perform an exact analysis which will take into account the influence of axial loads and variable

moment of inertia on member stiffness and fixed end moments, the effect of deflections on moment

and forces and the effect of the duration of loads. Another option is to approximately magnify design

moments.

STAAD has been written to allow the use of the first options. To perform this type of analysis, use the

command PDELTA ANALYSIS instead of PERFORM ANALYSIS. The PDELTA ANALYSIS will accommodate all

requirements of the second- order analysis described by IS:456, except for the effects of the duration of

the loads. It is felt that this effect may be safely ignored because experts believe that the effects of the

duration of loads is negligible in a normal structural configuration.


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Although ignoring load duration effects is somewhat of an approximation, it must be realized that the

approximate evaluation of slenderness effects is also an approximate method. In this method, additional

moments are calculated based on empirical formula and assumptions on sidesway

(Clause 39.7.1 and 39.7.1.1,IS: 456 - 2000).

Considering all these information, a PDELTA ANALYSIS, as performed by STAAD may be used for the

design of concrete members. However the user must note, to take advantage of this analysis, all the

combinations of loading must be provided as primary load cases and not as load combinations. This is

due to the fact that load combinations are just algebraic combinations of forces and moments, whereas

a primary load case is revised during the P-delta analysis based on the deflections. Also note that the

proper factored loads (like 1.5 for dead load etc.) should be provided by user. STAAD does not factor the

loads automatically.

Beam Design

Beams are designed for flexure, shear and torsion. If required the effect the axial force may be taken

into consideration. For all these forces, all active beam loadings are prescanned to identify the criticalload cases at different sections of the beams. The total number of sections considered is 13( e.g.

0.,.1,.2,.25,.3,.4,.5,.6,.7,.75,.8,.9 and 1). All of these sections are scanned to determine the design force

envelopes.

Design for Flexure

Maximum sagging (creating tensile stress at the bottom face of the beam) and hogging (creating tensile

stress at the top face) moments are calculated for all active load cases at each of the above mentioned

sections. Each of these sections are designed to resist both of these critical sagging and hogging

moments. Where ever the rectangular section is inadequate as singly reinforced section, doubly

reinforced section is tried. However, presently the flanged section are designed only as singly reinforcedsection under sagging moment. It may also be noted all flanged sections are automatically designed as

rectangular section under hogging moment as the flange of the beam is ineffective under hogging

moment. Flexural design of beams are performed in two passes. In the first pass, effective depths of the

sections are determined with the assumption of single layer of assumed reinforcement and

reinforcement requirements are calculated. After the preliminary design, reinforcing bars are chosen

from the internal database in single or multiple layers. The entire flexure design is performed again in a

second pass taking into account of the changed effective depths of sections calculated on the basis of

reinforcement provide after the preliminary design. Final provision of flexural reinforcements are made

then. Efforts have been made to meet the guideline for the curtailment of reinforcements as per IS:456-

2000 (Clause 26.2.3). Although exact curtailment lengths are not mentioned explicitly in the design

output (finally which will be more or less guided by the detailer taking into account of other practicalconsideration), user has the choice of printing reinforcements provided by STAAD at 11 equally spaced

sections from which the final detail drawing can be prepared.

Design for Shear

Shear reinforcement is calculated to resist both shear forces and torsional moments. Shear design are

performed at 11 equally spaced sections (0.to 1.) for the maximum shear forces amongst the active load


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cases and the associated torsional moments. Shear capacity calculation at different sections without the

shear reinforcement is based on the actual tensile reinforcement provided by STAAD program. Two-

legged stirrups are provided to take care of the balance shear forces acting on these sections.

As per Clause 40.5 of IS:456-2000 shear strength of sections (< 2d where d is the effective depth) close

to support has been enhanced, subjected to a maximum value of cmax.

Beam Design Output

The default design output of the beam contains flexural and shear reinforcement provided at 5 equally

spaced (0,.25,.5,.75 and 1.) sections along the length of the beam. User has option to get a more detail

output. All beam design outputs are given in IS units.

Beam Design

Beams are designed for flexure, shear and torsion. If required the effect the axial force may be taken

into consideration. For all these forces, all active beam loadings are prescanned to identify the critical

load cases at different sections of the beams. The total number of sections considered is 13( e.g.

0.,.1,.2,.25,.3,.4,.5,.6,.7,.75,.8,.9 and 1). All of these sections are scanned to determine the design force

envelopes.

Design for Flexure

Maximum sagging (creating tensile stress at the bottom face of the beam) and hogging (creating tensile

stress at the top face) moments are calculated for all active load cases at each of the above mentioned

sections. Each of these sections are designed to resist both of these critical sagging and hogging

moments. Where ever the rectangular section is inadequate as singly reinforced section, doubly

reinforced section is tried. However, presently the flanged section are designed only as singly reinforced

section under sagging moment. It may also be noted all flanged sections are automatically designed asrectangular section under hogging moment as the flange of the beam is ineffective under hogging

moment. Flexural design of beams are performed in two passes. In the first pass, effective depths of the

sections are determined with the assumption of single layer of assumed reinforcement and

reinforcement requirements are calculated. After the preliminary design, reinforcing bars are chosen

from the internal database in single or multiple layers. The entire flexure design is performed again in a

second pass taking into account of the changed effective depths of sections calculated on the basis of

reinforcement provide after the preliminary design. Final provision of flexural reinforcements are made

then. Efforts have been made to meet the guideline for the curtailment of reinforcements as per IS:456-

2000 (Clause 26.2.3). Although exact curtailment lengths are not mentioned explicitly in the design

output (finally which will be more or less guided by the detailer taking into account of other practical

consideration), user has the choice of printing reinforcements provided by STAAD at 11 equally spacedsections from which the final detail drawing can be prepared.

Design for Shear

Shear reinforcement is calculated to resist both shear forces and torsional moments. Shear design are

performed at 11 equally spaced sections (0.to 1.) for the maximum shear forces amongst the active load

cases and the associated torsional moments. Shear capacity calculation at different sections without the


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shear reinforcement is based on the actual tensile reinforcement provided by STAAD program. Two-

legged stirrups are provided to take care of the balance shear forces acting on these sections.

As per Clause 40.5 of IS:456-2000 shear strength of sections (< 2d where d is the effective depth) close

to support has been enhanced, subjected to a maximum value of cmax.

Beam Design Output

The default design output of the beam contains flexural and shear reinforcement provided at 5 equal ly

spaced (0,.25,.5,.75 and 1.) sections along the length of the beam. User has option to get a more detail

output. All beam design outputs are given in IS units.

Wall Design in accordance with IS 456-2000

Design of walls in accordance with IS 456-2000 is available in STAAD.Pro. Design is per formed for in-

plane shear, in-plane and out-of-plane bending and out-of-plane shear. The wall has to be

modeled using STAADsSurface elements. The use of the Surface element enables the designer

to treat the entire wall as one entity. It great ly simplifies the modeling of the wall and adds

clarity to the analysis and design output. The results are presented in the context of the

entire wall rather than individual finite elements thereby allowing users to quickly locate

required information.

The program reports shear wall design results for each load case/combination for user specified number

of sections given by SURFACE DIVISION (default value is 10) command. The shear wall is designed at

these horizontal sections. The output includes the required horizontal and vertical distributed

reinforcing, the concentrated (in-plane bending) edge reinforcing and the link required for out-of-plane

shear.


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Description of the Tutorial Problem

The structure for this project is a single bay, single story steel portal frame that will be analyzed

and designed. The figure below shows the structure.


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BASIC DATA FOR THE STRUCTURE


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Description of the Tutorial Problem

The structure for this project is a 2 bay, 2 story reinforced concrete frame. The figure

below shows the structure. Our goal is to create the model, assign all required input,and perform the analysis and concrete design.


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Description of the tutorial problem

The structure for this project is a slab fixed along two edges. We will model it using 6

quadrilateral (4-noded) plate elements. The structure and the mathematical model areshown in the figures below. It is subjected to selfweight, pressure loads and temp erature

loads. Our goal is to create the model, assign all required input, perform the analysis,and go through the results.


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