Elastic section modulus is incorrectly calculated for I section with cover plates for design as per

First Affected Version:
 Found in Version:
Fixed and Released in Version:
 Area: Steel Design as per AISC ASD 9th Edition
 Issue #:1110683

Problem Description

For a wide flange section having top and/or bottom cover plates, the elastic section
moduli Sy & Sz about Y & Z axes respectively, are calculated incorrectly when used with the AISC ASD (9th Edition) code. The effect of this is an overestimation of the section bending capacities which may result in an unconservative design.

The issue will be observed when all of the following conditions exist:
1) The member is designed to the AISC ASD (9th Edition)
2) The member is assigned with a wide flange profile that has additional cover plate(s)
3) The member is subject to forces that cause major and/or minor axis bending moments

The error does not occur when wide flange sections without cover plates are used for design by AISC ASD (9th Edition) code but occurs only when the wide flange sections with “top and/or bottom cover
plates” are designed. Note that the error is more pronounced when using sections with larger cover plates.


No workaround is available as of now for this defect.


The defect is already addressed and a fix is available in STAAD.Pro CONNECT Edition V22 Update 5 (