Spike in pushover analysis compared to test data.

[jarrar]

Hello!

I am modeling a pushover anaylsis for a fiber section using concrete07 and steel02. I am using data from the PEER data base (https://nisee.berkeley.edu/spd/servlet/ ... tml&id=346) for column "A2". i have got pretty good results but there is a weird initial spike in the low displacement region.

I have attached the model and the data that i got. what could be causing this?

[STKO Team]

You have to understand exactly the behavior of your specimen at the initial stage.
There can be many factors why its initial behavior is softer than your model: bar-slip, initial cracking, different initial modulus, imperfection in the constraints, wrong tensile strength, etc...