Constitutive model for thin-walled H-sections bent about weak-axis considering local buckling. (June 2020) - Cheng, Xin
Abstract: Since earthquakes occur in random directions, the seismic behavior of thin-walled structures about the weak-axis cannot be ignored, thus the corresponding constitutive model is necessarily needed. To achieve sufficient calculation accuracy and efficiency, the constitutive model of thin-walled steel H-sections, based on moment-curvature curves in the sectional level, is proposed in this paper. Firstly, the validated FEA models were utilized to conduct the parametric studies, where the effects of strain hardening rate and loading protocol on the constitutive model were fully discussed. Based on a large number of moment-curvature curves derived from the FEA models results, the undetermined parameters of the constitutive model were identified. The constitutive model provided precise predictions on hysteretic responses of H-sections, with the unfavorable coupling effects of plate interaction and local buckling fully considered. According to the different buckling mechanisms of H-sections based on the experimental and numerical results, the model was divided into two categories, including the post-buckling stage with decreased-reloading-stiffness (DRS) and increased-reloading-stiffness (IRS). Correspondingly, the proposed constitutive model contains one backbone curve and four types of hysteretic rules. Finally, comparisons of the proposed constitutive models with experimental and numerical results are conducted for further adjustments, which shows the model achieved high accuracy in a variety of loading scenarios.