How to unload in Pushover Analysis?

[KhaledSaif]

Hi all,

I am performing pushover analysis and when unloading I don't know how to set the displacement to 0 force position (the origin) so that I can push again from the same starting point.
I am just checking the concrete material (Concrete04) and I want to get the stress-stain diagram with loading-unloading.
I used "nonlinearBeamColumn" and pushed using "DisplacementControl".

Here is my code:

"pattern Plain 2 Linear {
load 2 0.0 -1000.0 0.0;
}
set iDmax "0 -0.00003 0.00003 ";
foreach Dmax $iDmax {
integrator DisplacementControl 2 2 $Dmax
analysis Static
set ok [analyze 28]
};

"


Thanks.

[fmk]

switch from displacementControl to LoadControl .. use the getTime command to figure out the current time which is the current load factor and use that as the loadcontrol increment or some factor of it if you want to unload in more than 1 step.

i.e. to unload to 0 in 10 steps somethng like the following:
set currentFactor [getTime]
set dLambda [expr $currentFactor/10.]
integrator LoadControl $dLambda
analyze 10