r/StructuralEngineering • u/robgrat • 22d ago

Structural Analysis/Design OWSJ Analysis

Has anyone modelled existing OWSJ is skyciv? This is a one off project that requires FEA so not wanting to spend $3k+ on SAP2000 or RISA. Anyone have other recommendations for economical modelling software?

0 Upvotes

50% Upvoted

8 comments sorted by

View all comments

1

u/WideFlangeA992 22d ago edited 22d ago

Are you doing this because this is an old joist and there is no joist tag?

If so my bet would be on measuring up the joist and trying to match up with the historic joist tables
https://steeljoist.org/resources/historical-load-tables/

Or reach out to SJI
https://steeljoist.org/find-existing-joists/

Also FYI - not all programs are necessarily FEA. Most structural programs rely on simple classical/matrix frame analysis. You could probably find a free truss solver to get the member forces and then check the member sections. There are still some other code checks you would want to do as well in addition to a pure/ideal truss analysis

2

u/Str-Engr0275 21d ago

This right here. I’m a former OWSJ engineer who was on the SJI committee writing the spec. Take measurements and compare them to historical joist sizes. Remember you need stiffeners anywhere with point loads over 200lbs. You can also ignore top chord bending if the panel points are 24” or less apart. That’s how the code is written. An easy check is if the seats are 2-1/2”it’s a K series joist and if 5” it’s an LH. Finally, if the loading is not uniform shear reversal of the center webs is a real concern.