Dear All, Just a brief introduction about the Diaphragm Design for Lateral Forces in case of Major Earthquake Areas: Please correct me where I am wrong: There are two types of forces in a member 1- Out of Plane Forces (out of plane behavior) 2- Inplane Forces (inplane behavior) Followings are the major components for design purpose in any structure a- Foundation b- Shear wall c- Column d- Beam e- Slab Foundation : We design it mostly for out of plane forces Shear wall : We design