Design of high performance concrete corbels

Abstract

Currently, concretes of higher compressive strengths have been produced and increasingly used by designers and contractors for both reinforced and prestressed concrete construction. The design of concrete corbels using the strut-and-tie model considers two failure modes: failure by crushing concrete in the strut and by yielding of the main steel reinforcement. To consider the failure by diagonal tension, a third equation is included in the truss plastic model proposed by Rogowsky and MacGregor. To use the truss plastic model, an efficiency factor is applied to reduce the effective concrete strength. An efficiency factor is proposed in this paper for high performance concrete. The proposed model using the new efficiency factor gives an improved correlation with experimental data. Based on the test results reported from literature review, the design method proposed by AFREM for high stregth concrete corbels is modified in this paper to make design of high strength concrete corbels more reasonable. The comparison with experimental data shows that the modified AFREM model predicts fairly well the shear capacity of the corbels.