A question concerning Ram Elements and the unity check for WT members. I have a truss structure with WT members as the chords. These members are under a combination of axial load and bending. I created the model in STAAD and exported to Ram to check it (Staad required for client but I am more familiar with Ram). I am getting different answers for the unity check of the bottom chord. In examining the results the loads and capacities are very similar but the difference appears to be that STAAD uses eq. H2-1 while Ram uses eq. H1-1. When I spoke to the AISC help desk concerning a similar issue they noted that the H1-1 equation did not apply as the WT member did not meet the requirement of 0.1<(Iyc/Iy)<0.9 noted in the code section. Does Ram Elements check this requirement when choosing the interaction equation to use? I am not sure that this is the only reason for the different answers I am getting but seems like a good starting point as the Ram model is an export of the Staad model. Thank you for your help.
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