Impact performance of concrete beams externally bonded with carbon FRP sheets
The paper focuses on behaviour of concrete beams externally bonded with various surface configurations under static and impact loading. Beams were strengthened with FRP U-wraps (one and two layers) and fully wrapped (one layer) to investigate the effectiveness of different wrapping schemes. In total, twelve RC beams (1200 x 100 x 150 mm) were tested. Six FRP RC beams were tested under static loading (three point bending) for analysis of load-deflection behaviour, failure mode and energy absorption capacity. Six FRP RC beams were subjected to a free falling 580 kg drop hammer to investigate the impact behaviour in terms of failure mode, crack patterns, dynamic mid-span deflection and dynamic force. Controlled beams were used for comparison with strengthened RC beams. Experimental results confirm that increase in the shear reinforcement decreases the overall impact displacement, indicating that the shear properties influence the performance of the beams under impact loading. The outcomes also reveal significant improvements in static energy absorption capacity for wrapped FRP RC beams compared to controlled specimens. A change in failure mode was observed from shear critical to flexural-critical when RC beams were externally strengthened under both static and impact loading.
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