Reinforced-concrete beams retrofitted in shear with externally-bonded fibre-reinforced polymer: Development of a design model

摘要

This paper presents the results of a theoretical study of the parameters that affect the contribution of fibre-reinforced polymer (FRP) composite to the shear resistance of reinforced-concrete (RC) beams retrofitted in shear. To assess and analyse the variables that have the most significant effect on the shear resistance of RC members strengthened with externally-bonded (EB) FRP, the results of available studies reported in the literature are used. In addition to variables related to the mechanical properties of FRP and internal transverse steel reinforcement, the following influential parameters on the shear contribution of FRP are assessed in this study: (ⅰ) the shear span ratio; (ⅱ) the longitudinal-steel reinforcement ratio; (ⅲ) the compressive strength of concrete; and (ⅳ) the failure mode of RC beams shear-strengthened with EB FRP. This study shows that the effect of steel stirrups on the shear contribution of FRP is significant. However, the steel stirrups effect is not taken into consideration in existing codes and guidelines. In this paper, a design method is proposed that considers the effect of steel stirrups in addition to other influential parameters on the contribution of FRP to the shear resistance. Comparison with current design guidelines reveals that the proposed model achieves a better correlation with experimental results than current design codes and guidelines.