Design Process for a New Building

©COMPUTERS AND STRUCTURES, INC., BERKELEY, CALIFORNIA DECEMBER 2001

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Technical Note 2

Composite Beam Design Process

This Technical Notes describes a basic composite beam design process using this program. Although the exact steps you follow may vary, the basic design process should be similar to that described herein. Separate processes are described for design of a new building and check of an existing building. Other Technical Notes in the Composite Beam Design General series provide addi-tional information.

Design Process for a New Building

The following sequence describes a typical composite beam design process for a new building. Note that although the sequence of steps you follow may vary, the basic process probably will be essentially the same.

1. Use the Options menu > Preferences > Composite Beam Design command to choose the composite beam design code and to review other composite beam design preferences and revise them if necessary. Note that default values are provided for all composite beam design prefer-ences, so it is unnecessary to define any preferences unless you want to change some of the default values. See AISC-ASD89 Composite Beam De-sign Technical Note 17 Preferences and AISC-LRFD93 Composite Beam Design Technical Note 30 Preferences for more information about prefer-ences.

2. Create the building model, as described in Volumes 1 and 2.

3. Run the building analysis using the Analyze menu > Run Analysis command.

4. Assign composite beam overwrites, if needed, using the Design menu >

Composite Beam Design > View/Revise Overwrites command. Note that you must select beams before using this command. Also note that default values are provided for all composite beam design overwrites so it is unnecessary to define overwrites unless you want to change some of

Technical Note 2 - 2 Design Process for a New Building the default values. Note that the overwrites can be assigned before or af-ter the analysis is run. See AISC-ASD89 Composite Beam Design Techni-cal Note 18 Overwrites and See AISC-LRFD93 Composite Beam Design Technical Note 31 Overwrites.

5. Designate design groups, if desired, using the Design menu > Compos-ite Beam Design > Select Design Group command. Note that you must have already created some groups by selecting objects and clicking the Assign menu > Group Names command.

6. To use design load combinations other than the defaults created by the program for composite beam design, click the Design menu > Compos-ite Beam Design > Select Design Combo command. Note that you must have already created your own design combos by clicking the De-fine menu > Load Combinations command.

Note that for composite beam design, you specify separate design load combinations for construction loading, final loading considering strength, and final loading considering deflection. Design load combinations for each of these three conditions are specified using the Design menu > Com-posite Beam Design > Select Design Combo command. See Compos-ite Beam Design Technical Note 10 Design Load Combinations.

7. Click the Design menu > Composite Beam Design > Start De-sign/Check of Structure command to run the composite beam design.

8. Review the composite beam design results by doing one of the following:

a. Click the Design menu > Composite Beam Design > Display De-sign Info command to display deDe-sign input and output information on the model. See Composite Beam Design Technical Note 4 Data Plotted Directly on the Model.

b. Right click on a beam while the design results are displayed on it to enter the interactive design mode and interactively design the beam.

Note that while you are in this mode, you can also view diagrams (load, moment, shear and deflection) and view design details on the screen. See Composite Beam Design Technical Note 3 Interactive Composite Beam Design for more information.

Composite Beam Design Composite Beam Design Process

Design Process for a New Building Technical Note 2 - 3 If design results are not currently displayed (and the design has been run), click the Design menu > Composite Beam Design > Inter-active Composite Beam Design command and then right click a beam to enter the interactive design mode for that beam.

c. Use the File menu > Print Tables > Composite Beam Design command to print composite beam design data. If you select beams before using this command, data is printed only for the selected beams. See AISC-ASD89 Composite Beam Design Technical Note 27 Input Data, AISC-LRFD93 Composite Beam Design Technical Note 41 Input Data, AISC-ASD89 Composite Beam Design Technical Note 28 Output Details, and AISC-LRFD93 Composite Beam Design Technical Note 42 Output Details for more information.

d. Use the Design menu > Composite Beam Design > Verify all Members Passed command to verify that no members are over-stressed or otherwise unacceptable.

9. Use the Design menu > Composite Beam Design > Change Design Section command to change the beam design section properties for se-lected beams.

10. Click the Design menu > Composite Beam Design > Start De-sign/Check of Structure command to rerun the composite beam design with the new section properties. Review the results using the procedures described in Step 8.

11. Rerun the building analysis using the Analyze menu > Run Analysis command. Note that the beam section properties used for the analysis are the last specified design section properties.

12. Click the Design menu > Composite Beam Design > Start De-sign/Check of Structure command to rerun the composite beam design with the new analysis results and new section properties. Review the re-sults using the procedures described in Step 8.

13. Again use the Design menu > Composite Beam Design > Change Design Section command to change the beam design section properties for selected beams, if necessary.

Technical Note 2 - 4 Check Process for an Existing Building 14. Repeat Steps 11, 12 and 13 as many times as necessary.

Note:

Composite beam design in the program is an iterative process. Typically, the analysis and design will be rerun multiple times to complete a design.

15. Select all beams and click the Design menu > Composite Beam Design

> Make Auto Select Section Null command. This removes any auto se-lect section list assignments from the sese-lected beams.

16. Rerun the building analysis using the Analyze menu > Run Analysis command. Note that the beam section properties used for the analysis are the last specified design section properties.

17. Click the Design menu > Composite Beam Design > Start De-sign/Check of Structure command to rerun the composite beam design with the new section properties. Review the results using the procedures described above.

18. Click the Design menu > Composite Beam Design > Verify Analysis vs Design Section command to verify that all of the final design sections are the same as the last used analysis sections.

19. Use the File menu > Print Tables > Composite Beam Design com-mand to print selected composite beam design results if desired. See AISC-ASD89 Composite Beam Design Technical Note 28 Output Details and AISC-LRFD93 Composite Beam Design Technical Note 42 Output De-tails

It is important to note that design is an iterative process. The sections used in the original analysis are not typically the same as those obtained at the end of the design process. Always run the building analysis using the final beam section sizes and then run a design check using the forces obtained from that analysis. Use the Design menu > Composite Beam Design > Verify Analysis vs Design Section command to verify that the design sections are the same as the analysis sections.