Behavior of Concrete Deep Beams Reinforced with Inclined Web Reinforcement around Different Opening Shapes

Abstract

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.