Analysis of influencing factors on shear behavior of the reinforced concrete deep beams

Abstract

A database including 833 specimens on reinforced concrete (RC) deep beams with shear failure is presented in this paper. Comprehensive influences of web reinforcement ratio, shear span-to-depth ratio, depth-to-width ratio, and compressive strength of concrete on the shear behavior of deep beams are discussed. It is found that the normalized shear strength of deep beams decreases with an increase of the shear span-to-depth ratio and this trend is affected significantly by the concrete strength, depth-to-width ratio, and web reinforcement ratio. Besides, the restrictions on minimum web reinforcement and minimum sectional size are investigated. It is found that the restrictions on minimum web reinforcement and the minimum sectional size are significantly affected by the web reinforcement ratio and are closely related to the reinforcement strength and concrete strength. However, the effect of the strength ratio of concrete to shear reinforcements on the limit of the amount of web reinforcements has been ignored in current codes. The characteristic value of web reinforcement, considering the web reinforcement ratio and the strength ratio of concrete to shear reinforcements, is proposed. For the horizontal and vertical reinforcements, the minimum characteristic values of 0.54 and 0.25 are suggested as the restrictions on the minimum amount of web reinforcement, respectively. The maximum characteristic values of 1.5 and 1.7 are proposed as the restriction on the minimum sectional size. Moreover, an equation for the ultimate shear strength of deep beams corresponding to the minimum sectional size is also suggested. Compared with the relevant provisions of the current codes, the suggestions on minimum web reinforcement requirements and minimum sectional restrictions are better.