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I need to invert flexibility matrix to derive stiffness matrix , what is opensees command for inverting matrix?
thanks .

In this method we replace beam to column connection by a cruciform element that 4 nodes exist in corner of this element(this element has dimention in X and Y direction).when this connection is semi rigid we have a 12x12 stiffness matrix for this element according to 4 nodes (and 3 dofs in each nodes...

in each connection nodes have 3 dofs match to other element nodes, but stiffness matrix for this element is different from other element.how can apply this matrix ?
thanks.

Hi ;
I have a 12X12 stiffness matrix for each 2d frame connections;how can I add new element with this stiffness matrix to being assembled with other element;
Thank you very much.

Hello
I need to modeling semi rigid connection in portal steel frames(E.Bayo modeling of semi rigid connection or cruciform element)in opensees to pushover analysis.
Thanks