Experimental investigation for shear strengthening of reinforced self-compacting concrete beams using different strengthening schemes

Abstract

This paper investigates the performance of four different strengthening techniques used to improve the shear capacity of RC beams. Three of the four strengthening techniques used were near-surface mounted (NSM) using carbon fiber-reinforced polymer (CFRP) strips, welded wire mesh (WWM) and textile reinforced epoxy mortar (TREM). The fourth strengthening technique consisted of a u-shape jacket made of ultra-high performance fiber-reinforced concrete (UHPFRC). Seven RC beams made of self-compacted concrete (SCC) were tested using a four-point bending setup. One beam was designed with sufficient shear reinforcement and served as the control in this study while the remaining six beams were cast with sufficient shear reinforcement in one half and no shear reinforcement in the other half. One beam was tested as a shear deficient control without any strengthening. The remaining five beams were strengthened with NSM-CFRP strips at 90°, NSM-CFRP strips at 45°, NSM-TREM strips, NSM-WWM strips and UHPFRC jacketing. The test results of all proposed strengthening techniques showed an increase in the shear strength of the RC beams by 47%–56% compared to using steel web reinforcement. The increase in the shear capacity of RC beams using 15 mm UHPFRC jacket was comparable to the other strengthening techniques. The UHPFRC jacket is considered a promising technique that could be utilized in the repair and rehabilitation of shear deficient RC beams. In addition to increasing shear capacity, the strengthened RC beams' mode of failure altered from brittle shear failure to ductile flexural failure with increased stiffness. Analytical modeling was conducted to predict the shear capacity of tested beams, with results that closely matched experimental observations.