Steel Frame Design Procedure

Following is a typical steel frame design process that might occur for a new building. Note that the sequence of steps in any particular design may vary but the basic process will probably be essentially the same.

Note:  It should be noted that two design processes are available in CSiBridge:  superstructure design (on the Design/Rating tab) and design of the individual elements comprising the structure (the Advanced > Frame Design commands). This topic addresses the second design process.

  1. Use the Advanced > Frame Design > Steel > View/Revise Preferences command to choose the steel frame design code and to review other steel frame design preferences and revise them if necessary. Note that default values are provided for all steel frame design preferences so it is not actually necessary to define any preferences. However, review the preferences, and if necessary change them, to ensure they are acceptable.

  2. Create the building model. See Modeling Process for more information.

  3. Run the building analysis using the Analysis > Analyze > Run Analysis command. If desired, animate the deformed shapes and mode shapes in 3D perspective by clicking the Start Animation button in the status bar at the bottom of the screen. Animate shell structures displaying stress contours with the corresponding deformed shapes in full 3D perspective. While displaying mode shapes or deformed shapes, the vector being displayed can be instantaneously changed with the '+/-' buttons that will appear at the bottom of the screen. Use the Orb > Settings > Other Settings command to turn the Sound associated with the animation off (uncheck the Sound check box) or on (check the Sound check box).

  4. If needed, assign steel frame overwrites using the Advanced > Frames Design > Steel > View/Revise Overwrites command. Note that frame elements must be selected before using this command. Also note that default values are provided for all steel frame design overwrites so it is not actually necessary to define any overwrites. However, review them and if necessary change them to ensure they are acceptable.

  5. Designate design groups, if desired, using the Advanced > Frame Design > Steel > Select Design Groups command. Note that groups must have already been created by selecting objects and clicking the Advanced > Assign > More > Assign to Groups command.

  6. To use any design load combinations other than the defaults created by CSiBridge for the steel frame design, click the Advanced > Frame Design > Steel > Select Design Combos command. Note that user-specified design combos must have already been created by clicking the Design/Rating > Load Combinations > Expand arrow command.

  7. Designate lateral displacement targets for various load patterns using the Advanced > Frame Design > Steel > Set Displacement Targets command.

  8. Click the Advanced >  Frame Design > Steel > Start Design/Check of Structure command to run the steel frame design.

  9. Review the steel frame design results using one of the following methods:

If design results are not currently displaying, click the Advanced > Frame Design > Steel > Interactive Steel Frame Design command and then right click a frame element to enter the interactive design mode for that element.

  1. Use the Orb > Print > Print Tables command to print steel frame design data. If a few frame elements are selected before using this command, data is printed for only the selected elements.

  2. Use the Advanced > Frame Design > Steel > Change Design Section command to change the design section properties for selected frame elements.

  3. Click the Advanced > Frame Design > Steel > Start Design/Check of Structure command to rerun the steel frame design with the new section properties. Review the results using the procedures described above.

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

  1. Click the Advanced > Frame Design > Steel > Start Design/Check of Structure command to rerun the steel frame design with the new analysis results and new section properties. Review the results using the procedures described above.

  2. Again use the Advanced > Frame Design > Steel >  Change Design Section command to change the design section properties for selected frame elements, if necessary.

  3. Repeat the process in steps 12, 13, 14 and 15 as many times as necessary.

  4. Select all frame elements and click the Advanced > Frame Design > Steel > Make Auto Select Section Null command. This removes any auto select section assignments from the selected frame elements (if they have the Steel Frame design procedure).

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

  6. Verify that the lateral displacements are within acceptable limits.

  7. Click the Advanced > Frame Design > Steel > Start Design/Check of Structure command to rerun the steel frame design with the new section properties. Review the results using the procedures described above.

  8. Click the Advanced > Frame Design > Steel > Verify Analysis vs Design Section command to verify that all of the final design sections are the same as the last used analysis sections.

  9. Use the Orb > Print > Print Tables command to print selected steel frame design results if desired. In addition, view time history displacements in real time video using the CSiBridge video creation options.

Note: Design is an iterative process. The sections used to run the original analysis are not typically the same sections that are used at the end of the design process. Always run a building analysis using the final frame section sizes and then run a design check based on the forces obtained from that analysis. The Advanced >  Frame Design > Steel > Verify Analysis vs Design Section command is useful for making sure that the design sections are the same as the analysis sections.