Pushover Analysis

[Gabriele.Neri]

Dear STKO team,
I'm trying to perform a pushover analysis in the following model.
I'm getting always the same issue (represented in the image called "Foto 1"), and I can't get the capacity curve ( as it's shown in the image called "Foto 2")

Can you help me?

Thanks in advance

[STKO Team]

There are some mistakes in your file.

The first 2 I saw are:

1. Your gravity analysis is Displacement-controlled in Ux. Why? it should be a regular load control analysis.
2. Why are you discretizing each member in multiple finite elements while using the Hinge Radau Integration scheme?
   This is wrong. Just use 1 element if you want to use the Hinge integration

[Gabriele.Neri]

Thanks for the advice! I've changed from displacement control to load control. I was using displacement control in order to catch the post-peak behaviour.
Concerning the 2 point I can't understand what you wrote.. in the model I have well-defined plastic hinge length, in order to consider them properly in STKO I have to use Hinge-Radau scheme.

[STKO Team]

I was using displacement control in order to catch the post-peak behaviour

Ok, if you expect a softening behavior already at the stage of gravity load you can use Disp-Control, but in that case you have to control the vertical displacement, not the horizontal one.

Concerning the 2 point I can't understand what you wrote.. in the model I have well-defined plastic hinge length, in order to consider them properly in STKO I have to use Hinge-Radau scheme.

What I mean is:
Imagine you have a column whose total height is 3 mt. Then you define a plastic hinge length of 0.3 m. That is fine if you use a single FE for your column, so you will have 5 gauss points, of which the first and the last will be 0.3 m and the remaining will span the remaining 2.4 m of the column.
But if you discretize your beam in multiple FE, each one will have their own plastic hinges (I,.e. 2 hinges per FE).
Furthermore, as you discretize your column, the FE size will be too small to contain those 2 plastic hinges.

[Gabriele.Neri]

Now I understood, thanks for the support!

[STKO Team]

You're welcome