Calculation of Steel Diaphragm Behavior

The available approaches to diaphragm design are reviewed and it is concluded that for panels that fall within its scope, the best available approach is the one proposed by Bryan in Constrado Monographs, but there are certain deficiencies in this method as presently formulated. A modified approach is presented for a wide range of diaphragm types which satisfy the following conditions: (1) The diaphragm is rectangular in plan; and (2) it is regular in construction, in particular there are no opening of significant size. It is proposed that diaphragms satisfying the preceding criteria be termed simple diaphragms and such diaphragms need not be investigated by the more expensive methods of testing or finite element analysis because the theory described in this paper is quite adequate. Diaphragms which fall outside the scope of the preceding definition should be termed complex diaphragms and require a more comprehensive investigation. The basic design expressions are summarized and these expressions form a basis for diaphragm design.