A rational approach towards the design of FRP-reinforced concrete beams

ABSTRACT

Fibre Reinforced Polymers (FRP) bars offer a practical solution for various problems of traditional steel reinforcement not only because of the non-corrosive nature of FRP but ,also for their high tensile strength to weight ratio and wide range of material properties. However the failure of FRP-reinforced concrete beams is, usually, different from that of conventional steel-reinforced concrete ones. Recently, the authors reported the major effect of the crack path geometry, the crack width and the dowel action of FRP bars on the behavior and strength of FRP-reinforced concrete beams. In addition, an analytical model was developed by the authors to trace the beam shear-flexure interaction up to the formation of a failure mechanism. The model results, while matching the results obtained experimentally, pointed at a significant overestimation of the strength values obtained by most of the current design guidelines for FRPreinforced concrete structures. This over-estimation, which is mainly due to the neglect of the above-mentioned parameters, reflects the inadequacy of the inherited design philosophies of steel reinforcement to represent the real behaviour of FRP. Herein, a parametric study, based on the previously developed model, is presented. Various parameters have been considered such as shear span, beam depth, the percentage of shear reinforcement and the contribution of shear reinforcement at failure. The study reveals guidelines to control the failure location as well as to achieve the desired beam strength and mode of failure. Furthermore, the present study is believed to be an approach towards comprehensive guidelines for the design of FRP-reinforced concrete beams