'In addition to resisting superimposed gravity loads, precast concrete floor systems should be capable of transferring horizontal shear from earthquake or wind loadings to the main lateral load-resisting system. The floor is usually assumed to be infinitely rigid in its own plane and, therefore, capable of distributing horizontal shear to different lateral load-resisting units in proportion to their lateral stiffness. Compatibility is, thus, maintained at floor levels. Precast floor units composing such a floor system should be carefully connected together and to the lateral load resisting system to insure an adequate load path for structural integrity and safety. Three methods of construction are commonly used; these are cast-inplace topping, welded hardware, and grouted joints. This paper covers the case of untopped precast hollow-core floor systems utilizing grouted joints. A design example based on shear-friction criteria is given and supporting experimental data are presented.
