Comprehensive design of Composite Steel Joists, SJI-CJ Series is now available in the RAM Structural System. This knowledge article describes the modeling and design of Composite Joists.

RAM Manager

Like Steel Beams, the self-weight of Composite Joists may be accounted for in designs when the Composite Joist check box is selected in the RAM Manager Self-Weight criteria menu. By considering self-weight, the need to apply an estimated joist self-weight as a surface load in RAM Modeler as is usually done for non-composite joists, need not be performed (for standard joists the self-weight is not yet applied automatically). 

 

Modeling

Create the model as customary for any project in RAM Modeler. Under the Steel Joist mode, use the Add On-Grid, Add Off-Grid or Add Generation commands to layout joists on plan.

 

Select the Composite radio button and use the Single or Fence commands to lay out Composite Joists.

 

 



For existing models with regular joists, use the Change Properties command to convert non-composite joists to Composite Joists. Similarly for models with other materials such as steel, use the Change Material command to convert beams to Composite Joists.

 

   

 

Composite Joists modeled without specifying a size and/or joist depth are optimized for both size and/or depth. A size and/or depth may be assigned to Composite Joists using the Assign Size command.



Like all other members, Composite Joists can be subjected to depth restrictions using the Assign Size Restriction command. User-assigned joist depths override any size restrictions imposed on members.

 

RAM Steel Beam
Design Codes
Composite Joists may be designed according to the following US design codes only.

 

Criteria

In RAM Steel Beam, the Joist Criteria - Composite Joist tab may set optimization limits for the joists. Composite Joists to be optimized for depth would investigate depths at increments set by the Increment of Depth from the Min Joist Depth to the Max Joist Depth.


In an effort to be consistent, some of the composite stud criteria like Max Stud Spacing are also applied to Composite Joists. 

 

Design All / View Update

The View – Show Designs command displays designed member sizes.





Select the Process – Design All command to have the design check performed on all of the members and select the Process – View/Update command to select and view the results for an individual member. Use the View/Update dialog box to investigate alternate Top and Bottom Chord sizes, Fy, and Joist Depth. Toggle the Composite / Noncomposite radio button and Optimize or Analyze composite and non-composite design options. The View - Results command shows a detailed design report.

Specific design routines for composite joists are based on a Live Load deflection limit of the span/360. The user may specify alternate deflection criteria, and those deflection results will be expanded at the end of the design report, but the deflection ratio shown in the View/Update dialog, and any pop-up warnings, are based on this hard-coded L/360 limit. 

 

Use the Process - Summary Report command to generate both a summary report of all beam and joist designs printed to screen or text and the SJI Composite Summary schedule .csv and .txt files saved in the default Reports directory. Use the RAM Manager - Post-Processing - Installation Report command to show the location of the program default Reports directory.

Note: Composite Joist designs should be verified by SJI. To assist in this process, upon completion of preliminary and/or final Composite Joist designs, users should send their RAM model (e.g. “filex.rss” file), including any customized beam, column or deck tables, to SJI for verification and validation of the computer model.