Precast concrete bridge deck panels reinforced with glass fiber reinforced polymer bars

The present research investigates lightweight and normal weight precast concrete panels for highway bridges. The panels are reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. A benefit of precast concrete panels reinforced with GFRP bars for bridge decks is that they are essentially immune to environments where chloride-induced deterioration is an issue. Twenty panels constructed using lightweight and normal weight concrete reinforced with GFRP bars for flexure without any shear reinforcement were tested to failure. The variables investigated were concrete compressive strength, deck span, panel thickness and width, and reinforcement ratio. The experimental performance of lightweight precast GFRP reinforced panels versus normal weight precast GFRP reinforced panels was investigated in terms of shear capacity, deck deflections, and moment of inertia. The experimental results show that lightweight concrete panels performed similar to normal weight concrete panels; however, they experienced larger deflections under the same load and had a lower ultimate shear strength than normal weight concrete panels. An extended database of 97 test results including normal weight and lightweight concrete restricted to members reinforced with GFRP bars for flexure without any shear reinforcement was compiled. The extended database including 77 normal weight concrete members from literature, 8 normal weight concrete panels and 12 lightweight concrete panels tested in the current research; no lightweight concrete members reinforced with GFRP has been found. ACI 440.1R predicted smaller shear strength conservatism of lightweight concrete panels compared with normal weight concrete panels. A reduction factor has been recommended for the ACI 440.1R shear strength prediction equation when lightweight concrete is used. Modified Compression Filed Theory (MCFT) was also used for the prediction of ultimate shear strength of GFRP reinforced concrete panels. The comparison of prediction to the experimental results shows that MCFT can predict accurately the shear strength for both lightweight and normal weight concrete panels reinforced with GFRP bars. All the tested panels both normal weight and lightweight concrete panels designed according to ACI 440.1R satisfy the service load deflection requirements of the AASHTO LRFD Bridge Design Specifications. The experimental results indicate that the moment of inertia for precast panels reinforced with GFRP bars with initial cracks was less than the gross moment of inertia even before the cracking moment is reached. An expression for predicting deflection using a conservative estimate of the moment of inertia for precast concrete panels reinforced with GFRP bars is proposed. Using the proposed equation, a better deflection prediction is obtained for precast concrete panels reinforced with GFRP bars under service load.