help

[nicola27]

I have made a dynamic analysis of a reinforced concrete frame and my analysis has failed.
The error is:
Arpacksolver: Error with saupd info= -9999
Could not build an Arnoldi factorization. IPARM(5) the size of check thatenoughkspace and array storage has been allocated.
Warning DirectIntegrationAnalysis : eigen - EigenSOE failed in solve () missing fuction argoment at -@- in expression "pow(_@_,o.5).
What must I change?

[vesna]

There is a problem with your eigen analysis. Would you post part of your code where you do eigen analysis.

[nicola27]

Thanks vesna I think I have solved this problem, because I used the dof equal in the x direction.
Now I want to ask you:
I am doing a dynamic analysis of a reinforced concrete frame.
When I calculate the period of my structure with elastic elements, I have a period of 0.54 s.
when I calculate the period with sections fibers have a period of 0.9 seconds, Why?
I ask this because I want to set the damping in my analysis.

[nicola27]

When I do the Eigen analysis, I have to use equaldof in direction 2 3?

[nicola27]

how to make a rigid diaphragm in a frame 2d?

[vesna]

If your period is not the same your fiber section is not the same as your elastic one. You can assign Elastic material to your fiber section to check how different is the response from when you use elastic elements.

[vesna]

if your material is steel or elastic you can model the effect of the slab by using equalDOF command. In case of concrete, I do not recommended assigning any constraints as concrete sections are usually robust enough to provide enough axial stiffness to simulate the slab effect.