4.5.3. rigidDiaphragm command

rigidDiaphragm(perpDirn, rNodeTag, *cNodeTags)

Create a multi-point constraint between nodes. These objects will constraint certain degrees-of-freedom at the listed slave nodes to move as if in a rigid plane with the master node. To enforce this constraint, Transformation constraint is recommended.

perpDirn (int)	direction perpendicular to the rigid plane (i.e. direction 3 corresponds to the 1-2 plane)
rNodeTag (int)	integer tag identifying the master node
cNodeTags (list (int))	integar tags identifying the slave nodes