Modeling a 3D truss

[amd13]

I am trying to model a 3D truss in STAAD. The forces in the members do no match the hand calculations I was given. Does anyone have any ideas why they aren't matching up? (I tried to model the truss by specifying the diagonal bracing as truss members.)

 

[SteveGregory]

Is this truss a true 3D truss such as a space frame or is it really a 2D plane truss with top and bottom chord bracing diagonal bracing to the adjacent trusses on each side?

If it the latter, then why are you modeling the braces?

 

[amd13]

My truss is like a space frame.

I am relatively new to using STAAD, so any advice you have is greatly appreciated. Thank you!

 

[SteveGregory]

You might want to check out the STAAD example problems with space frames. Open the Help file and search "space frame". There are a few examples.

Steve

 

[edward1]

Most truss examples in textbooks have one end support as a roller and the other end support pinned. Be sure you are using the same boundaey conditions.

 

[desaintvenant]

Maybe you've been using self-weight load... Sometimes this let your model not matching hand calculations!

Alessio Spigarelli
Structural Engineer