G.8 Axial-Only Specifications
STAAD.Pro has several member specifications which allow you to designate axial-only behavior for members.
Note: A specific member can have either end releases (see G.7 Member and Element Release) or axial-only specifications (see G.8 Axial-Only Specifications) properties assigned. The last specification for a given member will be used. In other words, a MEMBER RELEASE should not be applied on a member which is declared TRUSS, TENSION ONLY, COMPRESSION ONLY, or CABLE.