It is the assumed diaphragm to transfer horizontal forces to the structure without slab in-plane deformations.

With Rigid Diaphragm Behavior;

  • Story masses can be defined at the center of mass of the slab.

  • Since the number of unknowns is low, rapid analysis is performed.

  • Beams do not receive axial force.

Preferred building types;

  • Gapless slab structures without plan irregularities

  • Structures in which story slabs safely transfer horizontal forces to the carrier system in their own planes.

The slab is considered to be in-plane infinitely rigid and does not change shape.

  • When we compare the rigid diaphragm and semi-rigid diaphragm models, different displacement values ​​are seen in the middle region of the models.

  • The maximum displacement in the rigid diaphragm version is 0.035 millimeters.

You can review page 93 of the ideCAD Finite Elements Guide.

Diaphragm Modeling Selection

To model a rigid diaphragm, select the diaphragm modeling method from the Analysis Settings dialog.

Display of Horizontal Loads

Behavior of Structure Under Vertical Loads