The OpenSees Community

Thank you Dr. Silvia.

I suspect this may be a bug in OpenSees. Very disappointed.

In the Example5, the structural period decreases after gravity analysis, which means the stiffness increases. This is too weird for me. Anyone help me?

Hi, basir
I've encountered similar problems now.
Have you resolved them?

Dear all
I'm analyzing a RC frame structure, and wondering why the structural period changed after gravity load analysis. If it should change as a result of change of material stiffness, then it should increase or decrease? Thank you.

Dear Silvia: I've changed all the element into nonlinearbeamcolumn and defined uniform girder load as many concentrated load. The TH analysis can obtain reasonable results but can only run for several seconds. Then it display many messages about "can not get compatible forces and deformations f...

All the sections has been run for moment curveture analysis. No problem.

The grounmotion file is processed already with PGA=1 and no units. So in the Pattern UniformExicition.. I set the 'factor' to 0.4g. I've tried using the 'nonlinearbeamcolumn' and removed the uniform load on girders. Then the computation failed at about 0.3s because of 'Can't obtain equilibrium withi...

This is the full code. Anyone help me? # Reinforced concrete multi-bay, two-story frame # Distributed vertical load on girder # Displacement-based beam-column elements # Gravity load analysis followed by transient analysis # Units: kg,m,sec ->> N,Pa wipe #-------------------------- # define GEOMETRY...

No. It seems that the scaling of ground motion does not influence the lateral displacement! Just in about 0.2s the lateral displacement runs to very high values (e.g. several times of storey height)

Yes, I've checked it for many times and can't found what's wrong. Even if I scaled the input acceleration to very low, the displacement result is still too large. How weird!

I'm doing nonlinear transient analysis of a simple one story-three bay RC frame. The lateral displacement result runs quickly to almost 100% storey height during first steps, which is very weird. I've checked the code and done the moment-curture analysis of column. The eigenvalue analysis is correct...

The former units is : Ton, mm, sec, N, .... The result does not converge.
Then the unit is changed into SI: kg, m, sec, N... The result converge.
I think both two unit system is right. The problem may lie in the program itsself.

I just encountered the same problem.
I modified the tcl file by using the unit system of SI: kg,m,sec,N...
The nonconvergence problem is solved.
But what is the reason? Numerical precision?

I just attached the code to this post. Anyone help me?