# 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 ... ```

perpDirn

direction perpendicular to the rigid plane (i.e. direction 3 corresponds to the 1-2 plane)

rNodeTag

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).

## Examples

rigidDiaphragm 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