Punching Shear Capacity of Double Layer FRP Grid Reinforced Slabs

Synopsis: The punching shear capacity of concrete slabs reinforced with threedimensional fiber-reinforced polymer (FRP) double-layer reinforcement cages composed of glass fiber-reinforced pultruded grating elements has been investigated using full-scale experimental tests and a number of different analytical models. Test specimens were full-scale prototype bridge deck slabs with varying end restraint and support conditions, differing dimensions, and two different FRP bar fiber lay-ups. The tests results were compared with the punching shear models in ACI 318, ACI 440, Eurocode 2, BS 8110, CEB-FIB MC90, JSCE, and a number of models proposed in the literature specifically for FRP reinforced slabs. Based on this investigation a new empirical model has been developed to predict the punching shear capacity of double layer grids having either restrained or simply supported edges and including an overlapping splice. The model is shown to give reasonably good predictions for both simply supported and restrained slabs.