What is the difference between Member Releases & Boundary Conditions?
Probably the greatest source of confusion to people doing stuctural modeling is the difference between a Member Release and a Boundary Condition. A Boundary condition describes how a node is attached to the external world around it. The boundary condition says whether or not a NODE can translate or rotate. In contrast, a Member Release describes how a BEAM element is attached to a NODE. The member release says whether or not the beam to node connection will transfer shear, moment, or axial forces. In application, a boundary condition applied to a node would be used to model a fixed or pinned support condition, while a member release applied to a beam element would be used to model a fixed or pinned beam to column connection.
