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.

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 (ρt) from 0.3 to 0.5 increased the shear capacity by up to 54%. In addition, increasing the flange width-to-web width ratio (ρb) 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.

The objective of this paper is to experimentally and analytically estimate the influence of inclined reinforcement placed above and below web openings having different shapes in reinforced concrete (RC) deep beam. Twenty RC deep beams had the same overall geometric dimensions were tested under two-point top loading. Test variables included amount of inclined reinforcement, opening shape (circular, square, rectangular and relatively new type rectangular with fillet edges) and shear span-to-depth ratio. The relationship between the amount of inclined reinforcement and the opening size was expressed as the effective inclined reinforcement factor. As this factor was increased, the behavior of tested beams improved, where the crack width and its development decreased, and the ultimate load increased. The improvement rate of ultimate load with increasing effective inclined reinforcement for beams with rectangular openings having fillet edges was higher than that with sharp edges. Beams with opening having square, circular, or rectangular with fillet edges shapes and having effective inclined reinforcement ratio above 0.085 and 0.091 under shear span-to-depth ratio 1.0 and 0.6, respectively had higher ultimate load than that of corresponding solid beams. The effect of inclined reinforcement on enhancing the behavior of deep beam with opening increased as the shear span-to-depth ratio decreased. The ultimate load of tested beams was estimated using upper-bound analysis of the plasticity theory and compared with the test results. It is shown that the prediction has a consistent agreement with the experimental results.