Experimental study and parameter determination of cyclic constitutive model for bridge steels

Weathering bridge steel Q345qDNH and regular bridge steel Q345qD were experimentally studied under mono-tonic and cyclic loadings. Loading conditions included monotonic tension, compression, and twelve different pat-terns of cyclic loading, and were designed according to the load characteristics of the steel structure. Monotonic and cyclic hysteresis behaviors of these two steels were compared and the Ramberg-Osgood model was used to fit the hysteresis skeleton curves. Based on the experimental data, the isotropic-kinematic hardening parameters considered in the Chaboche model were calibrated and numerically verified when simulating cyclic hardening behavior. The results indicated that both the Q345qDNH and Q345qD steels have exhibit distinct yield plateaus and high energy dissipation capacity with well-stacked hysteresis curves. These two structural steels exhibit non-linear combined-hardening characteristics and hardening phenomena were observed to be more pronounced at the beginning of cyclic loading. The cyclic hardening properties of each grade of steel depend on their material microstructure, strain amplitude, and previous strain history. The hardening parameters verified in the Chaboche model can be used to accurately predict the stress-strain responses under cyclic loadings, and to study the inelas-tic responses of the steel bridges under conditions of vibration, fatigue, and earthquakes. (c) 2021 Elsevier Ltd. All rights reserved.