Mechanisms of shear resistance of one-way concrete slabs reinforced with FRP bars

The shear behavior of concrete reinforced with fiber-reinforced polymer (FRP) but without web reinforcement is potentially the most critical case in shear-prone applications due to the brittle nature of the concrete and reinforcement and, as such, requires special attention. A total of 16 one-way reinforced concrete slabs reinforced with glass- and carbon-FRP bars in addition to steel-reinforcement were constructed and tested to failure under four-point flexural loading. Their structural behavior was observed and reported in terms of failure mechanisms, crack patterns, main shear cracks, and ultimate capacities. The test results confirmed the effect of the axial stiffness of longitudinal FRP reinforcement on shear strength. The use of high-strength concrete had a positive impact on the initial shear-cracking load and ultimate-load capacity. The influence of the reinforcement type, bar diameter, and bar shear stiffness on the mode of failure was determined and discussed. Most of the CFRP-reinforced slabs experienced brittle failure, while most of the GFRP reinforced slabs-with reinforcement axial stiffness equivalent to that of the CFRP reinforced slabs-kept their integrity even after failure, thereby avoiding brittle modes of failure.