Dependence of the cyclic response of structural steel on loading history under large inelastic strains

This paper presents a series of cyclic loading tests on structural steel materials under cyclic tension-compression at large inelastic strains with amplitude up to 20% (+/- 10%). A total of six different cyclic loading protocols were considered in this study. The effects of the loading history on the cyclic response of structural steels including strain hardening, stress-strain response, damage evolution and plastic energy dissipating capacity have been investigated. The test results show that structural grade steels of Q345B and Q420D have the same trend in cyclic hardening or softening behavior and the loading history has quite obvious effect on the behavior of cyclic hardening or cyclic softening. The effect of loading history on cyclic stress-strain response is obvious especially at low amplitude. The effect of pre-cyclic strain loading is more obvious than those of pre-single strain loading. The steel Young's modulus E generally decreases with the number of cycle increases and the degradation rate becomes faster and faster with the increment of strain amplitude level. The energy dissipating capacity is nearly the same for all loading protocols. The cumulative dissipated hysteretic energy is only related to the total experienced strains but irrelevant to the loading paths for structural steels under fully reversed cydic tension-compression at large inelastic strains with amplitude up to 20% (+/- 10%). (C) 2014 Elsevier Ltd. All rights reserved.