## Mechanical Behavior of a Double-Column Self-Centering Pier Fused with Shear Links
###### Abstract  
A double-column self-centering pier fused with shear links is a novel structure developed to reduce residual deformation and facilitate post-earthquake repair. With this novel structure, the seismic resilience of bridges can be improved, and the reliability of lifeline infrastructure can be ensured. This paper presents the proposed pier configuration and investigates the mechanical behavior of the pier. A simplified finite element model is established to develop the lateral force-displacement relationship under cyclic loading. Additionally, a theoretical model based on the matrix displacement method and the virtual work principle is proposed to calculate the lateral force-displacement skeleton curve. The rationality and reliability of the theoretical model are validated by the satisfactory agreement observed between the numerical and theoretical results. Furthermore, a series of parametric analyses are conducted to discuss the effects of key parameters. The outcomes of this work can serve as a reference for further development of the design method for the innovated pier. seismic resilience; self-centering pier; shear links; theoretical model +
Footnote †: journal: Applied Mechanics and Physics Letters  
_Applied Mechanics and Physics Letters_  
prestress tendons [8]. Subsequently, experimental and analytical studies were performed by many researchers to demonstrate the potential advantages of self-centering piers [9; 10; 11; 12; 13]. Corresponding results confirmed that unbonded poststensioning could effectively mitigate residual deformation. However, despite the desirable self-centering capacity, the energy dissipating capacity is less than satisfactory. Therefore, a hybrid system, a poststensioned structure assembled with additional energy dissipation, is proposed [14]. This system results in a flag-shaped hysteretic relationship. Many studies have been conducted for further validation of the superiority of the hybrid pier system and the development of various solutions for energy dissipation. In previous studies, the energy dissipating capability of the hybrid system was enhanced in two ways: (1) Embedding internal energy dissipation (ED) devices consisting of mild steel bars or shape-memory-alloy bars with unbonded length at the critical joint [15; 16; 17; 18; 19; 20; 21; 22]. Obviously, such internal ED devices are not readily replaceable if damaged after a major earthquake, which increases the difficulty of post-earthquake restoration. (2) Installing external ED devices (viscous energy dissipation, steel dissipater, aluminum bars, etc.) around the bottom of the piers [23; 20; 24; 25; 26; 27; 28]. However, the limited installation space for external ED devices restricts the development of energy dissipation performance. Moreover, the external ED devices located at the bottom of the piers are more vulnerable to other natural and artificial factors, such as corrosion from water, impacts from vehicles, or floating debris. Replaceable shear links have been successfully applied in buildings [29; 30; 31; 32] and bridges [33; 34; 35; 36; 37; 38] as sacrificial elements to dissipate seismic energy. Inspired by previous research, this work proposes a novel pier system, which combines the advantages of both self-centering piers and replaceable shear links. As shown in Figure 1, the pier system relies on unbonded prestress steel strands to provide self-centering forces and adopts shear links between the columns to act as reformative external ED devices. The shear link consists of two parts, i.e., the replaceable part and the pre-embedded part, which are connected by high strength grade 12.9 bolts. During a severe earthquake (E2 level earthquake defined in Chinese Code [39], the largest acceleration in the lateral acceleration response spectrum is 0.34 g), inelastic deformation is concentrated in the replaceable part of the shear link, while the damage of key components (bent cap, columns, footing, unbonded prestress steel strands, and the pre-embedded parts of the shear links) can be prevented.