Seismic Performance Assessment of Self-Centering Tall Piers: Cyclic Loading Test and Numerical Analysis

This paper introduces the cyclic loading test and numerical model of a novel self-centering (SC) tall pier. This tall pier system is connected to the girder and foundation, respectively, through pre-embedded unbonded post-tensioned tendons at both ends. The pier base features a cast-in-place expanded base to enhance the overturning resistance, while energy dissipation is achieved through externally replaceable energy dissipators (EDs). The energy-dissipating connection devices also serve as shear keys, reducing construction time and costs. Experimental and numerical results show that the SC tall pier has excellent seismic performance. After loading cycles with a maximum drift ratio of 4%, the tall pier is basically undamaged, and the residual displacement can be ignored. The designed EDs demonstrate a stable energy dissipation capacity. However, it is crucial to correctly select the diameter of the weakened section of the EDs to prevent premature fracture, which could compromise the structure's energy dissipation capacity. Additionally, unlike low-height piers, the bending deformation of the self-centering tall pier is significant and cannot be ignored in the experiment. Numerical results show that the increase in pier height enhances the self-centering capability of self-centering bridge piers, while reducing their energy dissipation capacity, delaying the initiation of base gap opening, and shifting the displacement mechanism from base rotation dominance to flexural deformation dominance.