chapter  8
34 Pages

Horizontal floor diaphragms

ByKim S. Elliott

The stability of precast concrete buildings is achieved in one of two ways. First, the horizontal loads due to wind are transmitted to shear walls or moment-resisting frames by the floor (and/or the roof) acting as a horizontal ‘deep beam’, or some other appropriate model, known as a floor diaphragm (because of its depth to floor area being small). Any type of floor construction may be designed and constructed to function in this way, but particular problems arise in precast concrete floors which comprise individual units, such as hollow-cored or double-tee floors, because of the localised manner in which they are connected together, as shown in Figure 8.1. If the floor is a solid construction, such as composite plank, these localised areas do not exist and the horizontal forces are spread right across the floor area. Precast concrete hollow-core floor slab diaphragm. (Courtesy Reinforced Concrete Council, Camberley (formerly Crowthorne), UK.)