A modified curve-approximated hysteretic model for partially concrete-filled steel tube bridge piers

A modified curve-approximated hysteretic model for partially concrete-filled steel tube (PCFST) bridge piers is developed based on the previous research work. The proposed model, which consists of a series of quadratic and cubic curves and takes into account the P-Δ effect, pinching behavior in unloading-reloading hysteretic loops, and deterioration of strength and stiffness, can be used to precisely describe complicated hysteretic behavior of cantilever-type PCFST bridge piers. Parameters of this model are calibrated on the basis of quasi-static cyclic test results. To verify the validity of the proposed model, a total of 12 pseudo-dynamic tests were carried out. The detailed comparisons of different seismic performance indices between experimental and numerical results, such as the maximum response displacement, the residual displacement, and the amount of energy dissipation, indicated that the proposed model can be an acceptable complementary and assisting tool for the nonlinear seismic response assessment of PCFST piers. [Display omitted] •A modified curve-approximated (SDOF-CA) hysteretic model is proposed for partially concrete-filled steel tube bridge piers.•The SDOF-CA model considers the P-Δ effect, pinching behavior, and deterioration of strength and stiffness.•Simulation using SDOF-CA model can faithfully reflect the hysteretic behavior of PCFST piers under cyclic loading.•The validity of the SDOF-CA model was verified by the pseudo-dynamic test of 12 PCFST pier specimens.•Displacement and energy dissipation of PCFST piers under severe earthquakes can be accurately estimated by SDOF-CA model.