Shear Strengthening of RC Beams Using Fabric-Reinforced Cementitious Matrix, Carbon Plates, and 3D-Printed Strips

Abstract

Existing reinforced concrete (RC) structures suffer from degradation in their structural capacity. These structures require strengthening and retrofitting to integrate sustainability and improve their serviceability and durability. RC members strengthened with fiber-reinforced polymer (FRP) composites usually suffer from FRP debonding; therefore, researchers proposed several types of sustainable materials to overcome the shortcomings of FRP composites. Limited experimental studies have been conducted for shear strengthening of RC beams using sustainable fabric-reinforced cementitious matrix (FRCM) composites; moreover, the application of 3D-printed strips in strengthening RC beams has never been established. The current research experimentally investigates the efficiency of FRCM composites, 3D-printed sheets (CD), and CFRP plates (CP) in strengthening RC beams that are weak in shear. Various strengthening configurations were adopted, including vertical, oblique, zigzag, and several-slanted layouts. Eight simply supported beams were prepared to find the most efficient shear-strengthening configuration and material for RC beams. Test results showed that FRCM and CP are both efficient for shear strengthening in terms of maximum load capacity, initial stiffness, and ductility. However, CD showed a limited effect on enhancing the performance of shear-strengthened beams. The best shear enhancement was found in the beam strengthened with vertical CP, with improvements in load-carrying capacity, stiffness, and ductility of 43%, 23%, and 23%, respectively. The vertical and oblique strengthening configurations were more efficient than the zigzag and several-slanted layouts. The ACI 440.2R-17 model yielded accurate predictions with an average (Vc, test/Vc, ACI 440) of 1.11.