Reliability-based Criterion for Maximum Reinforcement Ratio of Reinforced Concrete Beam Sections

Abstract

This paper presents a reliability-based approach for the maximum reinforcement ratio of reinforced concrete flexural members. The study was based on sensitivity analysis of beams at their flexural limit state. The statistical characteristics of strength parameters under the prevailing construction practices in Saudi Arabia are employed. The maximum reinforcement ratio specified by ACI 318M-95 is critically examined. At the maximum reinforcement and employing local materials (concrete and reinforcement), the probability of brittle flexural failure was found to be higher than that reported in literature. This is mainly attributed to the high yield strength of the reinforcement and low compressive strength of the concrete. Two approaches were proposed to control the probability of brittle failure. The first approach includes replacing the nominal strength values of reinforcement and concrete by the corresponding mean values in the ACI formula for maximum reinforcement ratio. The second approach includes determination of the acceptable probability of brittle failure at the limit state and calculation of the maximum reinforcement ratio from the relationships developed in this study.