fbd_inv error with pinned beams

[seismosoft]

Dear iliya56,

As explained in our previous message, moment releases in frame elements cause convergence problems when the element gets in the inelastic range. This does not happen only in SeismoStruct, it happens to other FE packages as well (you can try it yourself, if you are not convinced), and it is related to the way the element stiffness matrix is treated, when end-releases are applied. As mentioned before, use the truss elements instead of frame elements with end-releases.

SeismoSoft Support