Many engineers tend to miss on the important concept of diaphragm design.

[1] Diaphragm refers to the horizontal structural system which enables transfer of lateral forces to the stabilizing units.

[2] It is very essential that diaphragm is designed to simulate the exact behavior as assumed in the analytical model.

[3] Diaphragm design becomes much more critical and interesting for non-monolithic floors plates like precast deck & steel/composite floors, as the possibility of re-distribution is negligible.

[4] Openings and floor cutouts need to designed & detailed to transfer the lateral forces through those.

The figure below shows a simplified approach for diaphragm design.

As given in the example the diaphragm can be designed as big flexural member of floor plate spanning between stabilizing walls and the corners are detailed accordingly.

This is a small post of diaphragm design. Any comments or suggestion are welcomed.