Different app. load value & no steps -> different results!?

[CMiculas]

Dear all,

I am performing some research on steel frames and joints.
Using the same type of integrator (load control) with the value of 0.1 and changing the number of steps and the value of the applied force, I obtain some very different results.
Please check the results file in my dropbox: https://www.dropbox.com/s/6pl5uaayymqeq ... s.JPG?dl=0

Can anyone please suggest me why the results are not the same or why they are so different?

Definition of the analysis (red curve):
...
set p1 -250000.0;
...
# Analysis Definition
constraints Transformation;
numberer Plain;
system BandGeneral;
# test NormDispIncr 1.0e-10 3;
algorithm Linear;
integrator LoadControl 0.1;
analysis Static;
analyze 14;

Definition of the analysis (yellow curve):
...
set p1 -350000;
...
# Analysis Definition
constraints Transformation;
numberer Plain;
system BandGeneral;
# test NormDispIncr 1.0e-10 3;
algorithm Linear;
integrator LoadControl 0.1;
analysis Static;
analyze 10;

[selimgunay]

It looks like you are applying 1.4 times larger force in the first one

[CMiculas]

yes, but that value of the force will be equal to the one in the second case, so both cases have the same value of the force, right?
case 1 => force x load control x no steps = 250 000 * 0.1 * 14 = 350 000
case 2 => force x load control x no steps = 350 000 * 0.1 * 10 = 350 000

[selimgunay]

In the first case, you may be applying on the first 10 steps as they amount to 100% according to the value of the parameter in the load command. Second one is correct. TO check you can update the second case as

integrator LoadControl [expr 1.0/14.0];
analysis Static;
analyze 14;

[Prafullamalla]

I believe that the displacement should be same for both the condition. Mistake might be during calculation of force while plotting the graph for particular displacement