Shear and Torsional Design of Reinforced Concrete Members with High-Strength Reinforcement

Abstract

Due to the similar design process for shear and torsion in RC members, the code limits on maximum yield strength for both shear and torsion are the same. However, the limiting values differ among different codes. For example, some codes limit the maximum yield strength of shear and torsional reinforcement to 420–800 MPa. This paper presents the experimental results of 73 RC members tested under shear and 42 members subjected to torsion, with high-strength reinforcement. The test results were carefully analyzed, along with other experiments from the literature, to investigate the behavior of RC members with high-strength steel under shear and torsion. Test results indicated that the crack width at the service load level was lower than the allowable limit of 0.41 mm even when members were reinforced with a yield strength of up to 700 MPa. The members under shear, with stirrups strength up to 600 MPa, showed shear tension failure prior to concrete web crushing. However, in the case of torsion, 18% of 153 specimens exhibited torsional compression failure when reinforcement yield strength exceeded 420 MPa. Based on these analyses of test results, a limiting value of 600 MPa for maximum yield strength of shear reinforcement is recommended in this study, whereas the current code-specified limit of 420 MPa on maximum yield strength is suggested to continue for torsional design until more supporting experimental evidence is available to increase this limit.