Overload damage mechanisms of GFRP-RC beams subjected to high-intensity low-velocity impact loads

This paper investigates the overload capabilities and damage mechanisms of Glass Fiber Reinforced Polymer (GFRP) bar reinforced concrete beams subject to high-intensity low-velocity impact loads. The overload condition of the beam is defined as the capability of the beam to sustain input impact energy exceeding its quasi-static energy absorption capacity. Nine GFRP bar reinforced concrete (GFRP-RC) beams were tested under three levels of increasing input impact energy. The shear capacities of the beams were varied by using three spacings of the shear reinforcement. The midspan deflection histories, impact loads, reaction forces, and accelerations of the beams were measured. The crack patterns and failure modes were recorded and analyzed using a high-speed video camera. It was found that the beam shear capacity significantly influenced the type of cracks and the development of cracks under increasing levels of impact energy. Flexural and flexure-shear cracks were observed in the beams with higher shear capacities whereas shear cracks were observed in the beams with lower shear capacities. It was also found that higher beam shear capacities led to reduced residual midspan deflections and higher residual load carrying capacities of the beams. Design recommendations are provided for GFRP-RC beams subjected to high-intensity low-velocity impact events.