As is well known, in the current design codes, the shear strength of beams is calculated based on the modified truss theory, which does not consider the effects of the flange area of T-beams. The main objective of this paper was to gain a better understanding and enhance the experimental database of the shear behavior of RC T-beams and illustrate the contribution of the flange to the shear capacity of T-beams. To accomplish this aim, a specially designed experimental program was executed, and its test results were analyzed. The main investigated variables were flange dimensions (thickness and width) and its reinforcement (longitudinal and/or vertical). Nineteen simply supported beam specimens were tested to failure under a load configuration made of two concentrated loads. Eighteen specimens had T-shaped cross-sections, while one specimen had a rectangular cross-section for comparison purposes. The items monitored during testing included the development of diagonal cracks, concrete strains, reinforcement strains, maximum loads, and deflections. Test results showed a notable increase in the shear strength of T-beams compared to rectangular beams with the same web size. For the range of variables investigated, increasing the flange thickness-to-beam depth ratio (ρ_t) from 0.3 to 0.5 increased the shear capacity by up to 54%. In addition, increasing the flange width-to-web width ratio (ρ_b) from 3 to 5 increased the shear capacity by up to 19%. It was also shown that the results of three-dimensional finite element (FE) analyses using ANSYS compared reasonably well with the test results for all specimens. Finally, based on the test and FE results, a simplified method that accounts for the contribution of the flange to shear capacity was proposed.

This research predicts the shear strength of reinforced concrete T-beams with flanges under compression stresses using nonlinear finite element (FE) analysis. A FE model is developed and verified against specially designed experiments (beams with varying flange width and depth). Results of the FE models were found to be in excellent agreement with their corresponding experimental results. The average load capacity and deflections (FE/experiments) ratios were 1.03 and 0.87, respectively. We then conducted an extensive parametric study to investigate the structural performance of flanged beams under the effect of two concentrated point loads. This parametric study examined four parameters: flange dimensions, longitudinal reinforcement in flange, concrete compressive strength, and shear span to depth ratio. Our findings indicated that the presence of compressed flanges in T-beams increases the shear strength by up to 260% of the shear strength of the web alone. The shear strength of flanged beams increases with the increase in flange dimensions, where the effect of flange thickness is more pronounced than that of flange width. Moreover, the presence of longitudinal reinforcement in the flange enhanced the beam's shear strength by up to 40%, compared to similar beams without flange reinforcement. Additionally, the shear strength increased up to three-fold for various beam conditions when the shear span to depth ratio was reduced from 2.0 to 0.5. These findings provide valuable insights for designing and constructing reinforced concrete T-beams with flanges under compression stresses.

Waste tires are a significant environmental issue, and this study explores the use of crumb rubber concrete (CRC) as a sustainable alternative by incorporating waste rubber from discarded tires as a partial replacement for fine aggregate (sand) in concrete. Seven slab specimens were tested, including a control specimen and six rubberized concrete specimens with 25%, 50%, and 75% rubber content in one-layer and two-layer configurations. The results showed that increasing rubber content led to a decrease in compressive strength and ultimate load capacity, with reductions of up to 85.5% in one-layer slabs and 50% in two-layer slabs compared to the control slab. However, CRC demonstrated a lower density, making it a potential lightweight material. Indirect tensile strength showed mixed results slightly increasing at lower rubber content but decreasing as more sand was replaced. While CRC offers significant environmental benefits, its mechanical performance limitations must be carefully considered for structural applications. Increasing rubber content also reduced workability, requiring adjustments in mix design. Despite these challenges, CRC has the potential to be a sustainable and eco-friendly construction material if optimized for strength and usability. Future research could focus on improving its mechanical properties through admixtures or alternative mix designs to enhance its application in modern construction