ENG 7704

Design of Steel Structures

Session 1 - 2007

Tamer SabrahPhD Candidate - Civil Engineering Discipline

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STAAD PRO 2004 SOFTWARE

STAAD is a comprehensive structural engineering software that addresses all aspects of structural engineering – analysis, design, verification, and visualization. STAAD performs the analysis and design of the structure for different types of structures. Design of some types of connections can also be performed.Powerful and very effective analysis and design tool, is a MUST for every structural engineer (designer/field/contractor…etc.) !!

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STAAD Tutorials Scope

• Giving demonstration for how to use the software by showing the guidelines about the basic steps for static analysis.

• Each session will highlight some different aspects about the Staad program.

• Three to four sessions will be given during the semester. Relevant assignments are required to solve.

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About Staad

• STAAD has two main methods of modeling :(1) Input editor (script language) and/or (2) Graphical Interface Environment (GIE).

• STAAD manuals and more information can be found through the internet. www.reiworld.com

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Modeling of Structures in Staad• Space structure:

– Structural elements (members) are in the 3D (x,y,z), and thus the loads.

• Plane structure:– Structural members and loads are both exist in one- (2D) plane.

(X-Y for example). (Tension, compression, bending can exist).• Truss structure:

– A special case of the plane structure, where all the members aretruss (link) members. (i.e. Tension or Compression members).

• Floor structure:– Structural members are existing in a plane (for ex. X-Y); while

the loads are acting perpendicular to this plane (i.e. acting parallel to Z-axis).

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Tutorial No.1ANALYSIS & DESIGN OF STEEL TRUSS

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TUTORIAL NO.1: STEEL TRUSS

A steel truss typical from several trusses supposed to cover a certain area. The truss has a cantilever part its span equals 4.0m. The proposed truss depth is 3.0m.The loads as shown, are concentrated at the truss joints. The values of its load case are shown. Use all the data you take in the Steel Course for analysis and design.

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Main Steps of ModelingEntering job information.Building model geometry.Defining member properties, sections.Assigning loads (load cases, combinations..)Defining pre-analysis print out, analysis type, and post-analysis printout.Defining design requirements.

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How to Start the Program?

From Start Menu - Select the STAAD.Pro icon from the STAAD.Pro 2004 program group.

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The opening pop-up screen!

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Select from here the units,

that we will deal with.

Assume that we have mm,

kN.

For a new file, select the

type of structure you want

to solve. Here select truss

type.

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The STAAD Graphical Environment will be invoked and the following screen will appear:

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1. ENTERING JOB INFORMATION.

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X

Y

How to Define the Truss Geometry?

One of the methods that you can create construction lines,

and then draw on these lines the truss members.

Noting that the number of

construction lines is excluding

first line.

2. Building Model (Structure) Geometry

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Other methods to create the model geometry:Other methods to create the model geometry:

• Enter the nodes (node by node) according to their

coordinates.

• Create a grid and define nodes at the intersections of this

grid, and then connect in between.

• Draw the frame in AutoCAD. Save the file as ( . DXF) file

type. From inside the STAAD Import that file.

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After clicking Snap Node/Beam, use the mouse and connect between nodes created at the intersections of construction lines.

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How to see the Diagram Labels (ex. Node numbers, beam numbers, etc.?

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Node and beam labels are a way of identifying the entities we have drawn on the screen, and very useful when dealing with the output results.

REMEMBER TO SAVE YOUR WORK FREQUENTLY

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Property:In which we can define or choose sections propertiesof the members of the truss.Spec.:In which we can define or choose members’ specifications.

Support:In which we can define the supports properties (restraints).

Load:In which we can define the applied loads, load cases, load combinations.

MaterialIn which we can define the material properties. (ex. E, density, etc.)

3. Defining member properties, sections.

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Property:

Assume Preliminary Sections:

Using the Canadian steel tables.

All Bot. & Top Chords are one size

L 55 X 55 X 3

All diagonals & Verticals are one size

L 45 X 45 X 3

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Assigning the sections created to the model

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Supports

By clicking on the support icon

the shown window will appear.

We have to create new kinds of

supports.

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X

Y

Hinged or Pinned support

Restraints (Fx, Fy, Fz)

<defaults>

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X

Y

(Fixed but) Support

All directions are restrained

or fixed and we choose what

are the directions that we

want to release.

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Use the mouse and click on the nodes according to its support type as shown below

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The creation and assignment of load cases involves the following two steps: 1. First, we will be creating all 3-load cases.2. Then, we will be assigning them to therespective members/nodes.

4. Defining Loads

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For example:

Dead Load Case can be Load Case No. 1

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Live Load Case can be Load Case No. 2, and Wind Load is the load case No. 3

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Load Combinations for Ultimate limit states (National Building Code)

0.5L + 0.25S(1.0D + 1.0E)5

0.5S or 0.4S(1.25D or 0.9D) + 1.4W4

0.5L or 0.4W(1.25D or 0.9D) + 1.5S3

0.5S or 0.4W(1.25D or 0.9D) + 1.5 L2

1.4D1

Companion LoadsPrincipal loads

Load CombinationCase

“Limit States Design in Structural Steel” by Kulak and Grondin – pg. 14.

Also, we can define load combinations according to required.

For example, we can create a load combination:

1.25 D.L. + 1.5 L.L + 0.8 W.L.

We can create hundreds of load combinations … but we will follow the previously shown cases.

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Please note: In some installed copies of Staad you may find this screen for load combinations!

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In Dead Loads create the self weight definition

Self weight is defined in the negative - Y direction

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In each Load Case create the Nodal Loads on the truss as specified before.

Make sure of the directions of forces according to the global coordinates.

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D.L. CaseL.L. Case

W.L. Case

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Pre-Print

Analysis

Post-Print

In which we are choosing from different types of structural analysis. The analysis typewe are required to do is a linear static type.

In which we are telling the program what are the properties that we require to be recorded and printed in the output filesbefore performing the analysis.

In which we are telling the program what are the properties that we require to be recorded and printed in the output files after performing the analysis.

5. Defining pre-analysis print out, analysis type, and post-analysis printout.

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To specify the Analysis command, first go to Analysis/Print Page from the left side of the screen.

Then, click on the Analysis sub-page from the second row of pages as shown below.

Choose Statics Check and Click Add then Close.

Analysis

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After creating the command of (Perform analysis - Static check), we have to assign the members that wants to be this type of analysis for it.

Click Assign, and then use the cursor and choose all the members, thus all the members should be highlighted as shown below.

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Pre-Print To add the pre-print commands click

Define Commands

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PrePre--Print CommandsPrint Commands • Material Properties

•Support Information

•Member Properties

•Joint Coordinates

•….

•….

ADD which property

do you need and then use

cursor to Assign to which

members in the truss.4343

General Rule in STAAD:

When you find any of the commands

you have added are marked by the

question mark (?) that means that

you didn’t assign this command to

any element in the structure.

Then, you have to assign the command

to the required members.

After you assign, the (?) mark should

be changed to ( ).4444

PostPost--PrintPrintTo add the post-print commands click

Define Commands

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For example here we have chosen to print the support reactions,

member forces, joint displacements.

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• Support Reactions

•Analysis Results

•Member Forces

•Max Force

•…

•…

ADD which property

do you need and then use

cursor to Assign to which

members in the truss.

PostPost--Print CommandsPrint Commands

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6. Defining Design Requirements.Steps:1. To specify steel design parameters, go to Design | Steel Page from the left side of the screen. Make sure that under the Current Code selections on the top right hand side, Canadian is selected.

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There are many Design Commands in the STAAD Design subroutine.

Here, we will use only to Check Code, regarding adequacy of members.

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Analysis & Viewing Results

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Select the Run Analysis option from the Analyze menu.

When you select the Run Analysis option from the Analyze menu, the following dialog box appears: We are presented with the choice of2 engines: the STAAD engine and the STARDYNE Advanced Analysisengine. The STARDYNE Analysis engine is suitable for advanced problems such as Buckling Analysis, Modal Extraction using various methods, etc. STAAD engine is suitable for this tutorial. Click on the Run Analysis button.

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The solving process is shown in a pop-up screen!

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Visualization of Some Results

Note:

Generally, in any program, try to make some checks about the shapes of deflections,

BMD, SFD. Also check the level of reactions.

Just to make sure that there is no significant input error.

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Viewing the Output FileDuring the analysis process, STAAD creates an Output file. This file provides important information on whether the analysiswas performed properly. For example, if STAAD.Pro encounters an instability problem during the analysis process, it will be reported in the output file. Alternatively, we can select the File | View | Output File | STAAD Outputoption from the top menu.

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The Output FileIts name is <filename.anl>.

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As shown for example, below are

the results of the steel design check

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Any Questions ?Any Questions ?

Thank you...Thank you...

This tutorial can be downloaded from the following link :www.engr.mun.ca/~sabrah/

Browse to my teaching page for tutorials and assignments

5858©© T.SabrahT.Sabrah