Overcoming the brittleness of shear failure: A new FRP-RSC strengthening philosophy.

• A new shear-strengthening philosophy was proposed to overcome the brittleness of FRP shear-strengthened concrete beams. • Both the ductility and shear strength were significantly enhanced by the proposed strengthening philosophy. • The new strengthening philosophy would not obviously increase cost and technical difficulties. • A new model was proposed to predict the V f of beams strengthened by the new shear strengthening philosophy. Due to the linear elastic stress–strain behavior of carbon fiber reinforced polymer (CFRP), the ductility of CFRP shear-strengthened reinforced concrete (RC) beams will be significantly reduced. Compared with shear capacity enhancement, increasing the ductility of CFRP shear-strengthened RC members is a much more challenging task, and a satisfactory solution has yet to be found. This paper introduces a new methodology that combines the brittle fiber reinforced polymer (FRP) with ductile rubber support composite (RSC) to form the FRP-RSC strengthening system. The variable stiffness RSC can adjust the stiffness of the strengthening system, which is achieved by the changed shear transfer actions in FRP, transverse reinforcement and concrete. Eight specimens were tested to evaluate the effectiveness of the FRP-RSC strengthening method. Experimental tests demonstrated that the displacement ductility with this FRP-RSC technique was 2.15 times that of the conventional externally bonded (EB) FRP strengthening, reaching remarkably 5.24. The mechanisms for enhancements in ductility, deformability and shear capacity were revealed. Poor matches were observed between the predicted FRP shear strength contribution (V f) per existing models and test data. A new model that can predict V f of FRP-RSC strengthened RC beams was developed, and better agreements between predictions and experimental results were obtained. [ABSTRACT FROM AUTHOR]