STUDY ON THE KEY PARAMETERS OF THE JOHNSON-HOLMQUIST CONSTITUTIVE MODEL FOR CONCRETE

As for the quantitative analysis in protective engineering, it is a key issue to determine appropriate constitutive parameters of concrete to guarantee the reliability of calculation and design. For this purpose, theoretical analyses, experimental tests and numerical simulations are carried out to calibrate the parameters of the Johnson-Holmquist (JH) model for concrete. The key parameters of the JH model are identified preliminarily by sensitivity analysis. The three-segment empirical equation of state was determined by summarizing relevant experimental data from literature and statistical analysis. The method to obtain the failure surface parameters A, B, N, and S_max was established through pseudo triaxial tests, and the corresponding parameters of concrete with various strengths were acquired by material tests and literature data. The strain rate effect was analyzed based on the SHPB tests with passive pressures, and the fitting rate-dependent constant was presented at strain rates of about 200 s^-1-500 s^-1. Finally, the JH model parameters were recommended for engineering calculation, and three numerical examples were given.