SAP2000-Example 3D Steel Truss

Analysis and Design of 3D Steel Truss Using SAP2000 ACECOMS, AIT

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SAP2000 Tutorial Example

Analysis and Design of 3D Steel Truss Using SAP2000 Table of Content Objective ........................................................................................................................3 Problem ..........................................................................................................................3 Material ......................................................................................................................3 Geometry ....................................................................................................................3 Step-by-Step Solution.....................................................................................................4 Start Modeling and Define Grid Line.........................................................................4 Assign Frame Elements..............................................................................................6 Define and Assign Groups .........................................................................................8 Define and Assign Frame Section ............................................................................11 Assign Restraints......................................................................................................15 Define Load Cases....................................................................................................16 Assign Loads ............................................................................................................17 Analysis the Model...................................................................................................18 Design Steel Members..............................................................................................19

Analysis and Design of 3D Steel Truss

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Objective To demonstrate and practice step-by-step on the modeling, static analysis, design and optimization of 3D Triangular Steel Truss using AISC-ASD89

Problem Find the lightest steel pipe sections for primary and secondary members of 3D triangular truss as following details.

Material Steel Es = 29000 ksi fy = 36 ksi Poissons Ratio = 0.3

Geometry

15 @ 1.00m = 15.00

4 x LL= 1,000 kg

10

75 cm


0

100 cm

cm

Primary Members Secondary Members

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Step-by-Step Solution Start Modeling and Define Grid Line

Step 1-1 Start Model: Start up screen of SAP2000, select the working unit “Kgf-cm” from drop-down menu on the bottom-right of screen then click on New model.

or go to File >

Step 1-2 Define Grid Line: Define grid line only one bay of truss by entering grid line parameters as shown in above figure and click “OK”.


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Step 1-3: Back to main screen, showing gird line that has been defined from previous step. Close “X-Y Plane” window by clicking at top-right of screen.


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Assign Frame Elements

Step 2-1 Draw Frame Elements in Bay 1: Click on

to make cursor snap to grid

or go to Draw > Draw Frame Elements then cursor will line or joint and click on be changed from selection mode to draw mode. Draw frame elements as shown in above figure by single click at first end and double click on the other end one by one.


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Step 2-2 Select All Frame Elements: Change to selection mode by clicking on . Click on to select all elements in model then selection status will report “6 Joints, 12 Frames selected”.

Step 2-3 Copy Elements in Bay 1 to Bay 2-15: Go to Edit > Replicate. Enter X = “100” and Number = “14”. Click “OK”.


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Back to main screen showing all frame elements in bay 1 are copied to all the rest of bays.

Define and Assign Groups

Step 3-1 Select Primary Members: Click on to change from “3D” View to “XY Plane @ Z=0” View. Draw selection rectangular cover all members in this plan (selection status = “16 Joints, 15 Frames selected”)


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Step 3-2 Select Primary Members: Click on to move XY Plane elevation from Z = 0 to Z = 0.75. Draw 2 selection rectangular to cover all members along X-axis as shown in above figure. (Selection status = “48 Joints, 45 Frames selected”.

Step 3-3 Define and Assign “PRIMARY” Group: Go to Assign > Group Name. Enter “PRIMARY” in text box, click on “Add New Group Name” and click “OK”.


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Step 3-4 Select Secondary Members: Click on tion status = “48 Joints, 138 Frames selected”.

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to select all members. (Selec-

Step 3-5 Select Secondary Members: To deselect primary members, go to Select > Deselect > Groups, select “PRIMARY” and click “OK”. (Selection status = “98 Frames selected”)


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Define and Assign Frame Section

Step 4-1 Import Pipe Sections: Go to Define > Frame Sections. Select “Import Pipe” from first drop-down menu.

Step 4-2 Import Pipe Sections: Select steel section database file (extension with “.pro”). For this example select “Aisc.pro” and click “Open”.


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Step 4-3 Import Pipe Sections: Select all pipe sections by clicking on first section (“P.5”) and clicking on last section (“PXX8”) with holding Shift button in keyboard. Click on “OK”.

Step 4-4 Import Pipe Sections: Click on “OK” again in “Pipe Section” window. Back to “Define Frame Sections” dialogue showing all pipe sections are in “Frame Sections list”.


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Step 4-5 Define Auto Selection Section: Select “Add Auto Select” from second drop-down menu.

Step 4-6 Define Auto Selection Section: Select all pipe sections in “List of Sections” by clicking on first section (“P.5”) and clicking on last section (“PXX8”) with holding Shift button in keyboard. Click on “Add ->” to move all selected pipe sections from “List of Sections” list to “Auto Selections” list and click on “OK”.


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Step 4-7 Assign Auto Selection Section: Click on

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to select all members.

or go to Assign > Frame Sections, select “AUTO1” and click “OK”. Click on “AUTO1” sections are assigned into all members in model as shown in above figure. Click on

to change back to normal mode.


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Assign Restraints

Step 5-1 Assign Roller Support: Select 2 Joints at the first end as shown in above figure by clicking on them one by one. Click on straints, select

or go to Assign > Joint > Re-

and click “OK”.


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Step 5-2 Assign Hinge Support: Select 2 Joints at the other end as shown in above figure by clicking on them one by one. Click on Restraints, select

or go to Assign > Joint >

and click “OK”.

Define Load Cases

Step 6-1 Modify Load Case: Enter Load = “DL” and clicking on “Change Load”


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Step 6-2 Add New Load Case: Enter parameters as shown in above figure, click “Add New Load” and click “OK”.

Assign Loads

Step 7-1 Select Joints: Click on 4 Joints at the middle of truss one by one.


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Step 7-2 Add “LL” Load: Click on or go to Assign > Joint Static Loads > Forces. Select Load Case Name = “LL”, enter Force Global Z = “-1000” (minus for downward) and click “OK”.

Analysis the Model

Step 8-1: Click on to start analysis. SAP2000 will ask to save this model. Select folder and specify File name to save this model. Click on “Save”.


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Step 8-2 Start Analysis: Click on or go to Analyze > Run. Check error messages from "Analysis" window after analysis is complete.

Design Steel Members

Step 9-1 Select Design Code: Go to Options > Preferences, select “Steel” tab, select Steel Design Code = “AISC-ASD89” and click "OK"


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Step 9-2 Select Design Groups: Go to Design > Select Design Group, double click on “PRIMARY” and “SECONDARY” one by one to move these groups from “List of Groups” to “Design Groups”.

Step 9-3 Select Design Combo: Go to Design > Select Design Combo, SAP2000 will create load combinations according selected code from previous step and add them into Design Combos automatically. Select one of them and click “Show” to view defined load case and load factors. Load combination can be defined manually from Define > Load Combinations. Click “OK” to accept this default.


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Step 9-4 Start Design: Go to Design > Start Design/Check of Structure. SAP2000 will optimize by selecting the lightest section (W8x18 for this example) from the section group (“AUTO1”) which satisfies the AISC-ASD89 that can be shown by clicking

and selecting “Section” in “Frames”.

Click on and draw rectangular line cover the first end area to enlarge “3-D” view. In “3D” View shows SAP2000 will assign “P3” section to all primary members and “P1.25” to all secondary members.


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SAP2000-Example 3D Steel Truss

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