In many practical applications, openings in deep beams are essential for accommodating services like ducts, pipes and cables. However, openings can significantly disrupt the load-transfer mechanism and reduce the shear strength of the beam, potentially leading to premature failure. Strengthening techniques are thus used to restore or enhance the load-carrying capacity and structural performance of deep beams with openings. The effectiveness of a novel strengthening approach that combines reinforced engineered cementitious composites (ECCs) and externally bonded carbon-fibre-reinforced polymer (CFRP) sheets was investigated. ECC reinforced with galvanised steel wire mesh was applied to the beam sides, with steel anchors to connect it to the concrete. CFRP sheets were then glued onto the hardened ECC surface. ECCs are highly ductile, fibre-reinforced cementitious materials with superior crack resistance and energy dissipation capabilities. Externally bonded CFRP sheets provide additional shear reinforcement and confinement owing to their high tensile strength. Six reinforced concrete deep beam specimens were fabricated and tested to investigate the effects of opening shape (rectangular or circular) and size on shear capacity. Load–deflection responses, crack patterns and failure modes were obtained. A non-linear finite-element model, developed to simulate the strengthening technique, was validated using the experimental findings. The results of this work provide valuable guidelines for enhancing the performance of deep beams with openings using reinforced ECCs and externally bonded CFRP sheets.

This study aims to investigate the local elastic buckling behavior of simply-supported prismatic web plates under pure shear loading. Comprehensive finite element analysis is conducted to analyze the effects of various geometric parameters, such as tapering ratio, aspect ratio, and web slenderness, on the local elastic buckling behavior with simply-supported boundary conditions. An eigenvalue analysis is conducted to determine web plates’ natural frequencies and corresponding shape modes with varying geometric parameters. Particular attention is given to the effect of the slenderness ratio, since current formulas do not consider the impact of the slenderness ratio on the elastic shear buckling coefficient. A sensitivity analysis is conducted to examine the importance of the web slenderness ratio for estimating the critical buckling coefficient of a prismatic plate under pure shear loading. Finally, a formula of the elastic local critical buckling coefficient for a simply-supported prismatic web considering the web slenderness effect is proposed, which can be used in international codes.

In this study, the effectiveness was investigated of shear strengthening techniques in reinforced concrete (RC) deep beams incorporating stainless steel plates (SSPs). Four RC deep beams were tested under incremental static loading until failure to examine the proposed strengthening techniques. The key parameters considered in this study included the arrangement of the externally bonded SSPs. The experimental findings demonstrated that strengthening using SSPs led to substantial improvements in their performance compared to the unstrengthened control beam. The use of SSPs increased the ultimate shear capacity by 129 to 175% over the control specimen. Finite element models (FEMs) were developed to simulate the responses of the tested beams strengthened using SSPs. Parametric studies were then conducted using the validated FEM to investigate to identify the effects of the area of SSPs on the shear capacity of the beams. The parametric studies concluded that increasing the plate thickness resulted in the enhanced shear capacity of the deep beam specimens up to a critical point upon which the increases in the thickness have insignificant effects on the shear strength. The accuracy of the design equations given by European and American codes in predicting the shear strength of the deep beams is examined.