Shear strengthening of normal concrete deep beams with openings using strain-hardening cementitious composites with glass fiber mesh

Abstract

Reinforced concrete (RC) deep beams are used in offshore platforms, bunker walls, and building load-bearing walls. Web openings are often necessary for accessibility or essential services. However, enlarging these openings due to architectural or mechanical requirements or changes in building function can significantly decrease shear capacity, posing a serious safety hazard to the structure. This study proposes a novel shear-strengthening technique of Reinforced concrete Deep Beams (RCDBs) with different opening shapes by incorporating Strain Hardening Cementitious Composites (SHCC) and Glass Fiber (GF) mesh. The shear behavior of RCDBs without and with different opening shapes is investigated experimentally and numerically. Six RCDBs were tested under static loading until failure to investigate two key parameters: opening shape (rectangular, square, and circular) and opening width-to-beam depth ratio (0.28 h and 0.20 h). The cracking force, crack patterns, observed deterioration modes, peaked shear force, load-vertical displacement, elastic stiffness, and absorbed energy capacities of the tested beams are reported. The experimental results showed that the utilized strengthening technique significantly increased the ultimate shear capacity, elastic stiffness, and absorbed energy, with the rate of increase decreasing with the increase of the opening size. The circular openings demonstrate a better performance than rectangular and square openings. A finite element model (FEM) was created using ABAQUS software to simulate the behavior of the tested NCCBs and validated against the experimental results. Good agreement was observed between the finite element simulations and experimental results, demonstrating that the FEM was able to accurately predict the shear behavior of RCDBs with SHCC and GF.