## 1 Introduction  
As a part of Accelerated Bridge Construction (ABC) techniques, using a precast bridge pier can improve bridge construction in terms of rapidity, quality, and environmental impact [1, 2]. Currently, precast segmental piers are extensively utilized in urban and highway bridges, especially in areas of low-to-medium seismicity [3, 4]. However, the application of this technique in high-seisincity regions is limited, primarily due to its insufficient energy dissipation capacity [5]. It is acknowledged that the connections between precast segments are critical for creating structural continuity, thus impacting the seismic behavior of the structure during extreme ground motion. To this end, various connection types between segments are applied to strengthen the precast pier's seismic performances, such as grouted splice sleeves [6, 7, 8, 9], grouting corrugated pipes [10, 11, 12], grouted pockets [13, 14], grouted ducts [15], and post-tensioned tendons [16, 17]. Among them, grouted splice sleeves (GSS) are particularly notable and extensively employed, attributed to their generous construction tolerance and dependable one-to-oneenergy-dissipating rebar connections [18]. Significant experimental research focusing on precast segmental bridge piers employing grouted sleeve connections has been conducted within the academic community. [PERSON] et al. [19] conducted experimental research on three octagonal pier specimens. The results revealed that embedding the grouted splice sleeves within the column, as opposed to the footing, leads to superior ductility and energy dissipation capacity of the pier. [PERSON] et al. [20] conducted quasi-static tests on precast segmental piers with a square cross-sectional dimension of 600 mm \(\times\) 600 mm. The results indicate a significant influence of the axial compression ratio on the hysteresis behavior and ductility of the specimens. While precast segmental piers manifest a comparable lateral load-carrying capacity to their cast-in-place counterparts, a minor compromise in ductility is observed. [PERSON] et al. [21] conducted experimental research on a cast-in-place circular column and a circular column connected with grouted splice sleeves. Owing to the large cross-sectional area of the grouted splice sleeves in the column section, the stiffness at the bottom of the column is more significant than that in regular precast piers, leading to a relocation of the plastic hinge in the pier column. The displacement ductility of a pier column has been significantly improved. However, although the GSS connection provides an effective interconnection of rebar for precast segmental bridge piers, the concrete at the joint remains non-continuous, setting these piers apart from cast-in-place piers in terms of the overall integrity and seismic performance [22]. Extensive research indicates that precast segmental piers connected with a GSS connection exhibit inferior strength and displacement ductility compared to their cast-in-place counterparts [23; 24; 25; 26]. Furthermore, the premature failure of the slurry layer at the joints, coupled with the inferior ductility of the GSS connectors, resulted in a reduced energy dissipation capacity and displacement ductility for the precast segmental piers [27; 28]. Therefore, it is necessary to make appropriate improvements to the GSS connection method to enhance the seismic performance of precast segmental piers, making them suitable for use in areas with high seismic intensity. Moreover, current research on precast segmental bridge piers mainly focuses on single-column pier systems, while studies on frame-style two-column bents are less common [29]. Compared with precast segmental single-column piers, precast two-column bents are more complex. Single-column piers can be simplified into an equivalent single degree of freedom (SDOF) system under seismic activities, with the plastic hinge at the bottom of the pier column. However, the frame-style two-column bents exhibit different seismic performances.