# RigidDiaphragm command
This command is used to construct a number of Multi-Point Constraint (MP_Constraint) objects. These objects will constrain certain degrees-of-freedom at the listed constrained nodes to move as if in a rigid plane with the retained node.
```tcl rigidDiaphragm $perpDirn $rNodeTag $cNodeTag1 $cNodeTag2 ... ```
|
direction perpendicular to the rigid plane (i.e. direction 3 corresponds to the 1-2 plane) |
|
integer tag identifying the retained node |
$cNodeTag1 $cNodeTag2 ... |
integer tags identifying the constrained nodes |
NOTE: The constraint object is constructed assuming small rotations.
NOTE: The rigidDiaphragm command works only for problems in three dimensions with six-degrees-of-freedom at the nodes (ndf = 6).
## ExamplesrigidDiaphragm 2 2 4 5 6; constrain nodes 4,5,6 to move as if in the same x-z plane as node 2.
Code Developed by: fmk