Investigations on the influence of boundary and loading conditions on the shear resistance of FRP concrete beams without shear reinforcement

Although a large number of investigations on the shear behaviour of fibre-reinforced polymer (FRP) concrete members have been performed, most of the shear tests were conducted on simply supported beams that were subjected to one or two concentrated loads. It is, therefore, not possible to draw general conclusions from the results of such simple tests that can be applied to the shear design of structural members with different boundary and loading conditions. Inspired by recent investigations on the system effects in shear behaviour of reinforced concrete beams without shear reinforcement, a small experimental programme was performed that consisted of three FRP concrete beams without shear reinforcement and identical cross-sectional properties. The investigated parameters included system effects like the static system (i.e. simply supported and cantilever beams) and loading conditions (i.e. concentrated and uniformly distributed loads). The experimental results show remarkable differences with regard to the location of the critical shear crack and the shear resistance in the tested specimens. Based on this evidence and experimental observations from available shear tests of FRP concrete members collected from the literature, an extension of a shear model that was originally developed for steel reinforced concrete members was made. The proposed method can be effectively used to estimate the shear resistance of a large available test dataset and enables researchers to account for most cross-sectional parameters as well the influence of boundary and loading conditions.