P-M interaction for columns

VISHAL BHATIA · Post by **VISHAL BHATIA** » Wed Oct 10, 2007 7:06 pm

I am carrying out the modelling of a steel frame using I sections. I want to model the columns so that they exhibit the P-M interaction. Opensees doesnot specify P-M interaction diagrams for different materials. How can I get P-M interaction for steel I sections. Also, I am working with nonlinear Beam column elemnt. I will carry out the analysis in the nonlinear range.
Does the section aggregator command includes P-M interaction or it keeps them independent?

silvia · Post by **silvia** » Thu Oct 11, 2007 5:32 am

the only way to get pm interaction is to use a fiber section.

VISHAL BHATIA · Post by **VISHAL BHATIA** » Thu Oct 11, 2007 6:23 am

What is the procedure getting P-M interaction for steel columns using W steel sections. Can anyone please suggest the procedure of getting the P_M curve and using the same in nonlinear Beam Column Element?

Also while defining the nonlinear beam column element for steel girders, I gave the following command:

uniaxialMaterial Steel01 1 36 29000 0; #beams
section Uniaxial 3 1 Mz; #beams
element nonlinearBeamColumn 10601 60 70 5 3 1;

But it gives errors : compatibility of forces and deformations not obtained.

Can anyone please explain how to define the beam elements using nonlinear property?

silvia · Post by **silvia** » Thu Oct 11, 2007 6:50 am

please look at the examples.
you need to associate shear and other stiffnesses to your section/element.