Analytical and numerical simulation of seismic resilient rocking column with enhanced RC column and pre-pressed disc springs devices

Abstract

This paper presents a novel self-centering energy dissipating RC rocking column (SCERC) in which a steel tube protects the concrete from spalling and crushing at the column base. It incorporates an easily repairable pre-pressed disc spring self-centering device (SC) to restore the rocking column to its original position and a straightforward slip friction energy dissipation device (ED) to ensure adequate energy dissipation capacity. The working principle of the SC was investigated, and an analytical method was proposed. Subsequently, a theoretical hysteresis model for the SCERC considering different limit states is developed through reliable analyses. Lastly, the preliminary design parameters of the SCERC were determined, with numerical simulations conducted to validate the theoretical model. These simulations aim to explore the hysteresis characteristics, energy dissipation capabilities, and self-centering performance of the SCERC under different axial pressures and self-centering ratios. The results indicate that the theoretical hysteresis model was consistent with the numerical simulations, revealing that the SCERC exhibits a “flag-shaped” hysteresis response. The proposed SCERC displays satisfactory energy dissipation and self-centering characteristics. The SC provide sufficient restoring forces, with the EDs accounting for much of the energy dissipation. Plastic deformation was not observed in the concrete column, except for the unavoidable deformation occurring in the steel tube at the point of rotation. While a rocking column naturally possesses self-centering capabilities under axial forces, it requires SCs to counteract the negative stiffness caused by the P-∆ effect. As the self-centering ratio decreases, both the load capacity and energy dissipation capacity of the SCERC increase, leading to an increase in the residual deformation of the column; hence, the design should balance these two aspects for a suitable self-centering rate.