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Thank you, this will be very useful.

Ok... Definately using Transformation contraints. I've discovered that programming the member end fixity for conversion program to transfer a 3D static model (from Space Gass) into an OS input file is not going be easy anyway. Space Gass uses local member axes for end fixity while equalDOF is a glob...

Thank you both for your response. The reason I have the other nodes is to simulate end fixity for more complex models... In this model I have made it a simple as possible. I realize they are pointless, but it should still run right? Please explain your comment "if using Transformation 3 needs t...

Hi There, I am attempting to make a general conversion program to transfer a 3D static model (from Space Gass) into an OS input file. The biggest problem I appear to be having is with the element end fixity conditions. I insert another node at the end of each element and constrain the dof between th...

I appreciate your 2 cents. But shouldn't the additional damping from a damaged structure be taken into account by the Hysteretic model? Priestley would argue that the elastic damping should reduce because hysteretic energy dissipation begins to account for most of the structural damping... Fully und...

Thank you for your thoughts... It is very helpful for me to know that you can do an eigen value analysis at each time step. Have I understood correctly that this will mean that, for example, 5% of critical damping can be maintained for first mode response, even as the 1st mode frequency reduces in t...

Hello All, Is there a document/example I can read to understand how regional rayleigh damping works? I have been modelling a frame with zerolength elements for rotational springs at the beam-column joints with and without rayleigh damping assigned to the rotational springs, which results in 10% diff...

Got it... In the code I was running I had 2/3 in the expression for Asc (not 0.8 as shown above). This gave a result of Asc = 0, which was causing the problem. Tcl syntax must take some getting use to...

Hello, Can section aggregator be used to combine the flexural, shear and axial stiffness of an elastic member and be used as a force Beam Column element? Please see the following extracts from my code: # SECTION AND SPRING PROPERTIES # Columns set hc [expr 700*$mm]; # Column depth set bc [expr 300*$...

I just got. I traced it back to a MultiLinear Elastic rotational spring that simulates column-base connections in my frame model. These have a significantly higher initial stiffness than the beam-column connections, and a sharp transition from the initial stiffness to the second stiffness. This tran...

Yes... Also I have changed to the Krylov-Newton algorithum, which seems to be much more stable. I manage to get about 7s of run time before it crashes. The recorder data for the moment-rotation response looks good... it achieved 3 points of stiffness change, but not the fourth... I am unsure that th...

I have narrowed down the problem. I am trying to use Elastic MultiLinear rotational springs. If I replace the Elastic MultiLinear material with a Elastic material the analysis runs fine... hence the problem seems to be my material definision. Please see the key extracts below: uniaxialMaterial Elast...

Great, thank you. I will keep looking

Hi there, I get a whole bunch of: WARNING BandGenLinLapackSolver: : solve <> - LAPACK routine returned 6 WARNING ModifiedNewton: : solveCurrentStep<> -the LinearSysOfEqn failed in solve<> .... Algorithm failed at time 0.01 ... -3 error flag... wrong # args: should be "set varName ?newValue?&quo...

Hello, I am just coming to grips with Opensees and have some questions regarding the Rayleigh Damping formulation. Firstly, the sort of structures I am analyzing have a non-linear elastic reponse. I have found that the best way to model the inherent (or elastic) damping in other programs (RUAUMOKO) ...