Curve-Approximated Hysteresis Model for Steel Bridge Columns

A curve-approximated hysteresis model of the lateral load-displacement behavior of steel bridge columns is proposed for nonlinear seismic response assessment of single-column-type bridges using single-degree-of-freedom (SDOF) analysis. Instead of multiple straight lines, a series of curves are adopted to precisely describe complicated force-displacement hysteresis behavior of the column. The P-delta effect, hardening effect in unloading-reloading hysteresis loops, deterioration of strength, and stiffness are taken into account. Parameters of proposed hysteresis model for three types of steel column specimens used in this study are calibrated by six quasi-static cyclic tests. To verify the accuracy of the proposed model, eleven pseudodynamic tests are conducted. By comparing the simulation and the test results, the differences between the predicted nonlinear seismic response using the proposed model and pseudodynamic tests are found to be, on average, 5% in maximum response displacement, 22% in residual displacement, and 4% in the amount of energy dissipation. (C) 2014 American Society of Civil Engineers.