topic Truss Calculation in Robot Structural Analysis Forum

Truss Calculation

john.bb — Thu, 04 Mar 2021 00:52:15 GMT

I tried to calculate a truss by defining the members as "truss" in advanced properties but when I try to calculate, it gives me instability errors.

Can someone help and say what's wrong with the model?

Thank you.

Re: Truss Calculation

Simau — Thu, 04 Mar 2021 10:31:01 GMT

@john.bb

Set upper and lower chords as simple bar and diag as only axial forces

Re: Truss Calculation

john.bb — Thu, 04 Mar 2021 12:44:11 GMT

Thanks for the answer, it solved the problem.

Any suggestion to avoid the huge shear strength I get on the upper chords at each end?

Re: Truss Calculation

Simau — Thu, 04 Mar 2021 18:26:03 GMT

This topic is outside the subject of this forum.
Before designing the structure, the calculation parameters must be configured for each type of bar. Here you have the lower and upper chords, purlins, bracings.
You must add horizontal bracing to hold the top chords and vertical bracing between trusses.
I also released the purlins.
I changed the orientation (gamma angle) of the chords so the weak inertia is in the plan of the truss.

The upper chord and lower chord types have been configured according to the modified structure.
However, it will be necessary to increase the profile of the chords.

File attached to serve as a working basis