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Designing castellated steel beams

Can you use Combine to design a castellated beam?

PROKON does not have a design module dedicated to castellated beams. However, you can do some of the design checks using Combine as follows:

  • In the Section Database, go to the table for parallel flange (or taper flange) I-sections. Scroll to the bottom of the table and enter the overall section dimensions of the castellated section on a new line. For the web thickness, use an average value that will give the same overall cross-sectional area. The Section Database module will automatically calculate the section properties for the entered beam section. On the File menu, save the information as your new default database (this will make the new section available to to PROKON modules).
  • Use this new section in Single Span Beam, Frame or Sumo.
  • Use Combine to perform the member and section strength design checks for flexure and axial force.
  • Use hand calculations for additional shear checks in the web.


  • When entering the castellated beam section in the Section Database, you must enter it as a regular I-section. If you enter it as a custom section, Combine will have insufficient information available to perform the design checks.
  • The above procedure effectively models a section with a solid web. This should be a reasonable approach for flexural design. You need to check the performance of the open web in shear by hand calculations.
  • Cross-check your design results with the supplier’s database.

For detailed guidelines, see Design Guide 31, published by the American Institute of Steel Construction, 2016.

Let us know if castellated beams are popular in your region and we might add it to our development list.