Experimental investigation on the shear characteristics of GFRP reinforcement systems embedded in concrete

To mitigate the deterioration of steel-reinforced concrete members, a fiber-reinforced polymers (FRPs) system has been introduced and has increasingly been used to replace the conventional steel reinforcing bar. However, questions remain about the performance of the Glass Fiber Reinforced Polymer (GFRP) reinforcing bar in concrete with varied stress orientation and shape. The GFRP reinforcement is an anisotropic material that possesses low strength for the transverse direction. This paper presents the results of the shear performance of GFRP reinforcement crossing varied crack angles. Fifteen push-off specimens were tested to investigate the shear characteristics of the GFRP and steel reinforcement. Tests were performed with three varied orientations of steel and GFRP reinforcement embedded in concrete: 90, 45, and 135-degrees with respect to the shear crack plane. In addition, the group-effect of GFRP reinforcement is also investigated with two reinforcing bars. Results indicate that the contributions of aggregate interlock and GFRP reinforcement are significantly varied depending on the bar orientation. Varied orientation of the GFRP bar across the crack plane allows for different failure modes of the reinforcement and absorbed energy capacities. Maximum shear capacity is obtained in specimen with 135-degree orientation accompanying with minimized crack width. This indicates that 135-degree orientation promoted higher aggregate interlock and sufficient development of strength in the reinforcement.