How to assign open section to model?

[nuttaphon.B]

I'm already define rack element in element class, but I cannot assign this section to my model.

[z.gronti]

Dear nuttaphon.B,

As it is written in SeismoStruct's User Manual: "Two nodes need to be defined for these element types, representing the end-nodes of the element, thus defining its length, position in space and direction (local axis 1). A rotation angle or a third node is required so as to define the orientation of the element's cross section (local axes 2 and 3), as described in Global and local axes system."