Analysis of shear strength influencing factors in reinforced concrete deep beams: A modified calculating model

Abstract

The mechanical behavior of reinforced concrete (RC) deep beams is highly complicated, influenced by various factors. Current codes and standards have not adequately addressed the impact of multiple factors. In this paper, a database containing 800 RC deep beams with and without web reinforcement is collected. The analysis of the correlation between shear strength and various factors was conducted through grey relation analysis. An improved calculating model for the shear strength of RC deep beams was proposed, whose variables were concrete compressive strength, shear span to depth ratio, beam effective depth, longitudinal reinforcement ratio, and web reinforcement ratio. A comprehensive study was conducted on the size effect initially, ensuring that all specimens were standardized to the same size level when determining the parameter forms. It was found that the size effect exists in both members with and without web reinforcement. Based on this, factors related to the shear strength of RC deep beams without web reinforcement were adjusted by iterative analysis. In addition, the web reinforcement was considered and the shear contribution of web reinforcement was obtained. A comparison between the proposed model and other calculation models was conducted. The proposed model exhibits superior consistency with experimental values in its calculations, with the smallest Root Mean Square Error (RMSE) of 281 and the smallest Coefficient of Determination (R2) of 0.913, approaching 1. The proportions of various shear contributions were also analyzed, providing insights into the shear principles of RC deep beams.