A rigid member is a member element with a very high stiffness. This member type can be used to represent rigid boundary conditions in the model.
In order to avoid numerical problems, the stiffness of a rigid member is adapted to the rest of the structure. This member type is used for rigid nodal constraints, which also allow for nonlinear restraints, eccentricities, member elastic foundations, and member nonlinearities in contrast to the "Coupling" member type. Furthermore, it is also possible to apply a load on a rigid member.
They are often used to replace an eccentricity, to connect member elements with surfaces, or to model a nodal connection using "spoke wheels" in an FEA model.
