Shear Strength Model of Concrete Beams Based on Compression Zone Failure Mechanism

Abstract

In the present study, a unified shear-strength model based on a compression zone failure mechanism was developed to predict the shear strengths of nonprestressed and prestressed concrete beams. In concrete beams damaged by flexural cracking, concrete shear resistance is mainly provided by the compression zone of intact concrete rather than the tension zone with flexural cracking. In this study, the principal stress failure criteria of concrete were used to derive the shear capacity of the compression zone, considering the effect of the compressive stress developed by flexural moment. To address the contribution of the tension zone, concrete residual tensile stresses acting across the web cracks were considered. The proposed method was applied to existing test specimens with a wide range of design parameters. The results showed that the predictions of the proposed method agreed with the test results of nonprestressed and prestressed concrete beams. A design example was provided to demonstrate the application of the proposed method to the actual design.