Member – rigid support member (RSM)
This feature is aimed at simplifying and greatly increasing the speed of design in Member. The supports of the members must be defined with an option to restrain or allow warping. This is impossible to do for a general cross-section. That is why we do not allow the direct setting of boundary conditions of an analyzed member but force engineers to design connections. Another benefit of this approach is the direct effect of connection stiffness on a member design.
Engineers are used to designing members joint-to-joint and related members can cause confusion. It is very hard to set even a simple supported beam or axially loaded column using related members. Their boundary conditions and loading must be carefully thought through and the related members still influence the internal forces in an analyzed member by their stiffness. Using a rigid support simplifies input and increases the speed of calculation.
Simply define a connection to be a rigid support to alleviate the burden of modeling.