Shear ductility and transfer criteria of reinforced concrete beams with near surface mounted aluminium sections

Abstract

This study investigates the shear performance of reinforced concrete (RC) beams strengthened with Near-Surface Mounted Aluminum Tubes (NSM-ATs) through experimental and numerical analyses. Nine RC beams were tested under a three-point loading setup to evaluate the effects of key parameters, including the number of NSM-ATs (four or five), spacing (150 mm or 106 mm), the presence of mechanical expansion anchors (MEAs), and strip inclination angles (60°, 45°, or 30°). The experimental results demonstrated that the anchorage system significantly enhanced shear capacity by improving bond strength and delaying crack initiation. The most effective configuration—five anchored vertical NSM-ATs—increased the cracking load by 92 %, ultimate load capacity by 64 %, elastic stiffness by 200 %, and energy absorption by 223 % compared to the defective beam, even matching the performance of the fully reinforced control beam. Inclined NSM-ATs also improved shear resistance, with the 45° orientation yielding the highest ultimate load. A nonlinear 3D finite element model (FEM) was developed using ABAQUS and validated against experimental data, showing strong agreement in load-deflection behavior and failure modes. The findings highlight the effectiveness of NSM-ATs, particularly when combined with anchorage, as a reliable technique for shear strengthening in RC beams, offering improved ductility and load-bearing capacity for retrofitting applications. • Near-Surface Mounted Aluminum Tubes (NSM-ATs) enhance RC beam shear strength. • Five anchored vertical NSM-ATs (106 mm wide) significantly improved cracking load, shear capacity, stiffness, and energy absorption. • The anchorage system delayed crack formation and reduced propagation, enhancing ductility. • ABAQUS-based 3D finite element modeling confirmed experimental results. • This technique offers a cost-effective, durable, and eco-friendly approach for RC beam strengthening.