SHEAR-STRENGTH OF PRECAST PRESTRESSED HOLLOW SLABS WITH CONCRETE TOPPING

An experimental program was conducted to investigate the shear-carrying capacity of precast prestressed hollow slabs with concrete topping. Ten specimens of the composite member without shear reinforcement were tested as simply supported beams with static two-point loading. The parameters investigated were prestressing force, thickness of concrete topping, shear span-to-effective depth ratio, and tensile reinforcement ratio. Nearly the entire composite action against bending was observed from the measured deflection, strains of concrete and reinforcement, and slip between the precast and topping concrete elements, as well as cracking strength. Prestressing force in the precast element affects the shear cracking strength greatly but has considerably less effect on the ultimate shear strength. The measured shear cracking and ultimate shear strength can be approximated reasonably by conventional prediction methods for monolithic reinforced concrete with the use of effective web width at hollows in the precast elements and full width of the topping concrete, respectively.