What is a diaphragm in general, and what function does it serve in transferring

lateral forces in a building?

What is a flexible diaphragm?

What is a rigid diaphragm?

Highlight the main differences between a flexible and a rigid diaphragm.

Given the schematic Roof Plan shown below, assume:

The walls are cantilevered from their base;

The walls are $20$ feet high;

A total equivalent lateral force of $1,000$ kips is acting in each of the orthogonal

directions of the building at the roof level.

Determine the force which is acting on each wall at the Roof Level, in each of the two

orthogonal directions of the building for the following cases:

Assumed flexible diaphragm:

Assumed rigid diaphragm.