Roofs and floors which distribute wind or seismic loads to a building's lateral force resisting members are referred to as horizontal diaphragms. The interaction between a diaphragm and its vertical supporting elements must be considered, together with externally applied loads, when computing diaphragm strength requirements. Practical and analytical considerations in the design of diaphragms for earthquake loads are discussed. Diaphragm construction methods in use in the United States are described. Differences in strength and serviceability are pointed out.
