Rayleigh

[MichaelDupuis]

Hello everyone, I have a script which is doing a dynamic analysis of a simple sdof system. I am using the rayleigh command in the script as follows:
set alphaM 0.0;
set betaK 0.0;
set betaKinit [expr 2*0.05/$w];
set betaKcomm 0.0;

rayleigh $alphaM $betaK $betaKinit $betaKcomm;

The script was originally written for v2.2.0 and works fine in v2.2.0. However, for some reason that I can't discover, the exact same script when run in v2.3.0 is producing different time histories for both the elastic and inelastic analysis. I have narrowed the problem down to the rayleigh command. For some reason it is not doing anything in v2.3.0 and when I remove it from the script run in v2.3.0 it produces the same results as when run with it in v2.3.0.

Does anyone have any ideas?
Thanks

[tazarv]

Can you post all your script?
The coefficients for stiffness proportional part of Rayleigh damping are very small values. Make sure that your coef. are not integer especially your Omega ($w) if so, OpenSees with round them to zero.
Try this, calculate betaKinit manually and plug into the OpenSees with decimal point (e.g. set betaKinit 0.016).

I hope it works for you.

[fmk]

the problem was a result of the fact that the truss elements by default do not include any rayleigh damping .. this change was nessitated by the fact that there are multiple
truss elements used in the source code depending on dimensionlity and section/material options .. before the change some included rayleigh damping & some did not .. we nedded to make things consistant .. there is now an option -doRayleigh in the command to include it if the user wants it.