Large Accelerations during gravity analysis

[jaimercado]

Dear All

I am getting large accelerations at the nodes of a 2D structure during the gravity analysis. The type of analysis I am using is Transient with steps of 5.e-3 with a dt of 200 (this is to reach the 100% of the gravity load). So, since the gravity stage ends with acceleration at the nodes up to 5 m/s, the following dynamic stage started with those acc.

To solve this I am using the following for the gravity stage:
constraints Penalty 1.e20 1.e20
test NormDispIncr 1e-6 100 1
algorithm Newton
numberer RCM
system UmfPack
integrator Newmark $gamma $beta
analysis Transient
analyze 200 5.0e-3
loadConst -time 0.0;

I tried to change the system method but I am getting the same response.

Any thoughts?

Thanks in advance.

[giovannimilan]

Why do you wanna use transient for gravity?

I usually for static, based on the example I found in opensees wiki.

Have you seen them? like dynamic analysis on 2d steel frame

[jaimercado]

Thanks giovanni for you response.

I am performing a non-linear analysis since I am modeling a SSI. So a transient analysis is needed. I think i figured out the problem using Analyze 20 5.0e-2 instead.