P-delta effect

[quhui]

hello, everyone

I am calculating a RC cantilever column subject to cyclic horizontal displacement. I found that changing the axial load level on the column has no effect on the result.

What's wrong with my script? Would you like to give me some suggestion?

I have attached the part of applying load in my script.
Many thanks for your help!

===================================
# set the boundary conditions - command: fix nodeID xResrnt? yRestrnt?

fix 1 1 1 1

fix 2 0 0 0


pattern Plain 2 Linear {

load 2 0 -675000.0 0 -const ###change the gracvity loading has no effect
}


system ProfileSPD

constraints Plain

integrator LoadControl 0 1 0 0

test NormDispIncr 1e-2 150

algorithm Newton

numberer RCM

analysis Static

analyze 5

loadConst -time 0.0


pattern Plain 1 Linear {

#load nd? Fx? Fy? Mz?

load 2 1 0 0 ###applying horizontal displacement

}

[quhui]

The gravity load is applied first,and the fixed invariably during the calculating process.

I want to know whether the way I applying load is right?

if it is right, I want to know how to carry out the P-Delta effect in the opensees.

many thanks to you!

[silvia]

i'd follow the example in the examples manual on how to apply gravity.

[quhui]

Thank you!

the way that i apply gravity is right.

I should use geomTransf PDelta considering second-order P-Delta effects.

[pejman_opensees]

I would use corotational transformation through which you are not normally encounterd any convergence problem in cyclic analysis.