Tensile behavior of 400 MPa-grade anti-earthquake hot-rolled ribbed bar (HRB400E) over a wide strain rate range

Abstract

HRB400E reinforcing bar has been widely used in critical members of reinforced concrete structures due to its excellent ductility. However, an inadequate understanding of its strain rate behavior has restricted its application under extreme dynamic loading. To obtain the tensile strain rate behavior, dynamic tensile tests of the HRB400E reinforcing bar were carried out over a wide strain rate range between 0.00025 and 870 s−1. The test results showed that HRB400E steel has a significant sensitivity to strain rate. To predict precisely the dynamic increase factors for yield stress and ultimate tensile strength, the widely used Cowper-Symonds and Malvar models were modified. Moreover, the Mander model was fitted and modified to predict precisely the engineering stress–strain relationships. Finally, the constitutive models for the true stress–strain relationship were investigated. The frequently used Johnson-Cook model was confirmed to have a large prediction error over the wide range of strain rates examined in this paper. Thus, a new rate dependent constitutive model for the true stress–strain relationship was proposed, which was demonstrated to be highly accurate.