Rigid Member Offsets

Where members meet at the joints in a structure, there may be little distortion in the part of the structure that is common to more than one member. This is the "joint block" region. If the member cross-section dimensions are large, the very stiff joint block region may be relatively large. When rigid member offsets are used to model the joint block region the end of the member is considered to be connected to the adjacent node by an infinitely rigid link. The diagram below shows typical applications of rigid member offsets.

RIGID MEMBER OFFSETS

Microstran V8 permits the specification of rigid offset dimensions in either global or local axes. The orientation of the local axes used for specifying offsets may be changed by the offsets. In the example shown below, members 4 and 7 have rigid offsets specified in the global axis directions while members 6 and 9 have respectively the same offset values specified in the local axis directions. Although the local axis directions of members 7 and 9 are both changed by the rigid offsets, in the case of member 9, the reference axes are themselves changed by the offset values.

RIGID OFFSETS SPECIFIED IN GLOBAL & LOCAL AXES