Strain-Rate Effect and Constitutive Models for Q550 High-Strength Structural Steel

摘要

High-strength structural steel is the tendency in modern construction practice. In this study, quasi-static tension tests and dynamic tests for Q550 with strain rate from 0.00025 to 3831 s(-1) were conducted. The results showed that Q550 is dependent on the strain rate, keeping the flow stress increased as the strain rate increases, while Q550 has lower strain-rate sensitivity of flow stress than that of normal mild steel. Based on the experimental data, a proper constant for the key parameter, C, in Johnson-Cook model (J-C) was suggested. Then, a modified J-C model based on a rate-dependent parameter C (epsilon) was recommended to consider the influence of strain-rate effect. New constants of D and p governing the dynamic response of steel in the Cowper-Symonds (C-S) model were also suggested. The C-S model and J-C models with suggested constants provided in the paper were proven to have acceptable prediction accuracy for the dynamic increase factor of Q550. These results may be applied to study the dynamical properties of Q550 and related structural components for future engineering applications.