The OpenSees Community

Thanks for your reply. I guess in the current state, OpenSees can not return the stiffness matrix before performing analysis. As a suggestion, it would be great to achieve the stiffness matrix before analysis. I am not sure if it is possible.

Hi I would like to report a problem that I am not sure if it is a bug. I would like to obtain the stiffness matrix of a truss in openseespy. I use printA and FullGeneral system after ops.analysis. However, if the truss is unstable, it returns this error and quit the python console. It works properly...

Hi all. I want to learn more about reliability analysis features of OpenSees. So, I started with the youtube video of https://www.youtube.com/watch?v=Nsv5otRuWLw. When I tried to run the examples using my standalone OpenSees with ver 2.5. I failed because I got this error: invalid command name "...

Hi,

Did you find out what is the problem regarding this error?

It got solved, there is a problem in support nodes and it's ambiguously mentioned in the literature.

Dear selimgunay, All units are consistent and in SI. I modified the code as you suggested and replaced the Iz 2.9666e-6 with 8.3333e-07, but no improvement in the result can be seen. The output of the code is as follows, FullGenEigenSolver::solve() - the eigenvalue 9 is complex with magnitude 1.3884...

I tried to model a simply supported bridge, but I can't reproduce the results in the literature. The description of the truss is as follows, "To demonstrate the flexibility of the approach, a simply supported bridge is optimized for its weight minimization with several cases of frequency constr...

Dear Frank,
I considered the consistent mass and it worked like a charm. Thanks for your incessant help and suggestions. I'm also grateful for this superb OpenSEES that you and your colleagues provided for scientific use freely.

Dear Frank, First of all, thanks for your fruitful comment. I thought again and again about my problem and I'm now sure about that the mass matrix is not correct. An expert suggested me that my model looks ok but I have not yet added the lumped mass. He added that "this is done by declaring a m...

I want to obtain the natural frequencies of a benchmark truss which is famously known as 10-bar planar truss. It consists of 10 truss members and 6 nodes. Two nodes are its supports and other four nodes are free nodes. The modulus elasticity is 6.89e10 and the added non-structural mass to the free n...

As to my knowledge and not practically, I know that first of all you should download the latest stable source code from the repository and compile it with the corresponding MAKEFILE for the version of linux. TCL libraries are essential too. To download the source code from repository you should foll...

Hi, I want to model this 25 bar truss benchmark. the schematic of the benchmark and the loading conditions are attached. How can I define this kind of loading in my code? Because there are multiple loading on nodes 1 and 2. Is it possible with multiple pattern plains? In a one sentence, How can I mo...

First of all, thx for your reply. I'm repeatedly calling it in two sections; first I take stiffness matrix in a file with printA and I check the eigenvalues for stability and second, I run force/displacement analysis and it results in two files which include axial forces and displacement, so I guess...

correction : The code runs smoothly on Mac OS X but it crashes without any errors in Windows after hundreds of computations.

Hi, I have written a code to find optimal truss structure using evolutionary algorithms. Furthermore, these kind of algorithms are based on numerous computations. my code produces some text outputs and i read them from Matlab, these outputs are stiffness matrix,axial forces and displacements in node...