RSA_Piles rotation

[yaroosh]

Hello Everyone,

I am currently running a response spectrum analysis on a bridge model built on drilled shaft. The way I modeled the piles, is divided into 5' frames and assigned a line spring to each one. I had already calculated the PY and imported it into CSI Bridge.

However I have two identical piles and only the left one is rotating tremendously by about 940 rad/in. I cannot figure why. I checked restraints, the PY values but the Left pile acting in unstable way.

Any advise will be greatly appreciated.

Thanks!

 

[ukbridge]

There's not enough information to understand why the rotation is so large, some diagrams showing rotation and a deflected shape would be useful.

In general I don't like using "infinitely stiff" supports at pile bases, use springs instead for the pile vertical and horizontal stiffnesses. Even if you dont have these to hand you can eyeball them in, based on say 10-20mm vertical deflection and doing a small parametric study to check the sensitivity of these values.

Also be careful of units you use, are the springs assigned to the nodes or the elements?

gl