Punching Shear Failure in Double-Layer Pultruded FRP Grid Reinforced Concrete Bridge Decks

The use of pultruded fiber reinforced polymer (FRP) grids is being investigated as tensile reinforcement in concrete bridge decks. Three full scale simply supported concrete slabs reinforced with double layer pultruded FRP girds representing long span bridge decks were tested. Punching shear was the critical failure mode. The punching shear capacity was compared to the University of Wisconsin punching shear equation, developed for the grid system on shorter spans by Jacobson (2004), and the punching shear capacity as given by ACI 440 (2006). The Jacobson equation conservatively predicted the capacity for slabs with edge restraint and accurately predicted the punching shear capacity for slabs without edge restraint. The ACI 440 (2006) punching shear equation underestimated the punching shear capacity of the slabs.