Static and multi-impact performances of RC beams strengthened with large rupture-strain FRP composites

To solve the problem of inadequate plastic deformation capacity and energy dissipation of traditional fiber-reinforced polymer (FRP) strengthened structures under impact loading, this study proposes the use of novel large-rupture-strain fiber-reinforced polymer (LRS-FRP) materials combined with different strengthening schemes to improve the impact resistance of existing structures. This study conducted three-point bending and drop hammer tests to investigate the static and dynamic behaviors of flexure-dominated LRS-FRP-strengthened beams. Experiment results showed that the end-anchored FRP strengthening system at the beam soffit significantly improved the load capacity of beams under static loading and reduced the maximum mid-span deflection under impact loading, and the ductility factor of LRS-FRP strengthened beams under static loading was 2.7 times higher than that of the carbon-FRP (CFRP) counterpart. Specimens strengthened with a mid-span LRS-FRP wrapping scheme presented improved ductility and multi-impact performance. Specimens strengthened with a combined scheme enhanced the static load capacity and ductility of by 71.9 % and 159.7 %, respectively, compared to the unstrengthened beam, and exhibited the best energy dissipation capacity (23.8 kJ) under multiple impact loads. These findings from the test investigations can facilitate design guidance and evaluation methods for strengthening schemes for RC structures under impact loading.