FINITE ELEMENT MODELING OF REINFORCED CONCRETE DEEP BEAMS TO STUDY SIZE AND SHEAR REINFORCEMENT EFFECT

Reinforced concrete deep beams are structural members characterized by relatively small span-to-depth ratios and nonlinear stress distributions. Because of their high shear capacity and ability to transfer concentrated loads, they are commonly used in transferring girders, pile caps, offshore structures, and other critical structural applications. Their behavior differs from that of slender beams because shear deformation, disturbed regions, diagonal cracking, and compression strut action strongly influence their load-transfer mechanism.
This study investigates the effects of beam size, web reinforcement, and beam width on the nonlinear behavior of reinforced concrete deep beams. Three groups of specimens were considered, with variations in overall depth, section width, and reinforcement arrangement. The investigation focused on load–deflection response, crack initiation, plastic strain distribution, shear capacity, and internal compressive force paths.
A three-dimensional nonlinear finite element model was developed using ABAQUS, and the Concrete Damaged Plasticity model was adopted to simulate concrete cracking, crushing, stiffness degradation, and inelastic response. The numerical results were validated against experimental data in terms of load–deflection behavior, crack development, and failure response. The comparison showed a good agreement between the finite element predictions and the experimental results, demonstrating the reliability of the calibrated numerical model.
The results indicate that increasing beam depth and width improve stiffness, increase load-carrying capacity, reduce midspan deflection, and delays crack formation. Beams with increased width and without stirrups developed lower plastic strain and greater crack resistance than narrower beams with web reinforcement. These findings confirm the significant role of beam geometry in controlling the structural response of reinforced concrete deep beams and demonstrate the effectiveness of nonlinear finite element analysis as a tool for investigating their behavior.