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you are going to have to do an eigen analysis with both horiz and vertical masses, look at the eigenvectors and determine those which correspond to the vertical frequencies you seek. if there is liitle to no interaction between horiz and vertical movemnt of the structure they should be similar to wh...

to original poster .. what convergence test are you using .. i suggest NormUnbalance if you are not using it .. NormDispIncr is pretty much useless in dynamic analysis if you want to ensure equilibrium

simplest might be to orient the structure at 45 degrees and use normal constraints .. create a little function to return the transformed coordinates for the nodes and use those when creating the nodes or just use [expr ] in the nodes directly.

i suggest you try it and spit out the fibers and their locations to see what you generated. if you have complicated sections i suggest building the section i fiber at a time .. if repeated complex shaped sections, create procedures to do this.

the only way to determine damping forces when using modal damping is to determine from global equilibrium .. it is a pain to do but you need to record the ground motion, all nodal accelerations for which there is a mass, and the element end forces .. create a free body diagram and then utilize the f...

the fact that section axial force and element axial force is not consistent is a result of how the element force is calculated for a DISPLACEMENT based element" .. basically loop over all the gauss points in the element and combine the forces using the forces at the gauss points and the gauss p...

try changing solver to ProfileSPD and respond with the error you get when you run it

By PEER cbrinck means myself, the original developer of OpenSees and the person who last updated the copyright. The above license requirement for companies offering the opensees application as an online service you pay for, just mentioned by ponczek, is required as the UC lawyers have determined tha...

no simpler solution exists.

yes. it just sets aflag in the LoadPattern that tells it to keep the load multiplier the same from here on out.

i suggest you post a simple example outlining your problem .. you have provided not enough information to provide any guidance .. as you are a newbie, a simple problem will force you to understand how OpenSees works and will hopefully enlighten you as to the mistake you are making.

The programs will not give the same results. Typically the difference is small, a difference in some insignificant digits. Hoewever if matrix is poorly conditioned at stages in a nonlinear analysis the results can be larger at the end. Check on differences after first few steps, if very different yo...

error codes returned from lapack at start of analysis indicate the model is incorrect .. try a ProfileSPD solver and a PlainNumberer to see what dof has a problem, example: model basic -ndm 2 node 1 0 0 node 2 0 10 geomTransf Linear 1 element elasticBeamColumn 1 1 2 10 100 1000 1 fix 1 1 0 1 timeSer...

here is a simple script that does what you describe w/o error (hopefully). It is impossible to figure out your problem with code in other files. Hopefully you can sort out your issue from code below. If not repeat your problem in a SIMPLE example like below. model basic -ndm 2 node 1 0 0 node 2 0 10...

it is not a feature that is available from the command line .. it is of course something you could do in your script that creates the model