## 5 Conclusions  
This study focuses on the effects of the proposed GSS-GCT connection on the seismic behaviors of precast segmental two-column bents. Three scaled precast two-column bent specimens were fabricated and subjected to quasi-static cyclic tests. Furthermore, the capacity spectrum method was adopted to evaluate the seismic performance of the three bents under the different PGA levels. Several main conclusions can be drawn as follows.  
1. The bent B2-CIP failed with the buckling of longitudinal rebar and fracture of stir-rups. Plastic hinges manifested at both the bottom and top of the columns, with nearly identical lengths observed in both locations. The precast two-column bents B2-PGS and B2-PGT failed with longitudinal rebar fracture at the cap-column and column-footing joints, with openings observed at both the top and bottom seams. Notably, for the two precast bents, damage severity was markedly higher at the cap-column joint compared to the column-footing joint. The precast cap beam remained essentially elastic.
2. The load-carrying capacity and displacement ductility of the bent B2-PGS were marginally inferior to bent B2-CIP, attributable to the discontinuity in segment joints. Moreover, bents B2-PGS and B2-CIP exhibited nearly identical energy dissipation capacity and residual displacement. Nevertheless, using the GSS-GCT connection significantly enhanced the aforementioned four performance indicators of the bent B2-PGT, elevating its seismic performance under high-level earthquakes beyond that of the cast-in-place bent B2-CIP. Hence, precast segmental two-column bents with the proposed GSS-GCT connection could be suitable for high-seismicity regions.
3. Five levels of the damage state for specimens B2-CIP, B2-PGS, and B2-PGT were qualitatively and quantitatively divided based on experimental observation, which can be evaluated with lateral displacements \(\delta\).
4. Displacement performance under a given level of peak ground acceleration was assessed using the capacity spectrum method. It was found that all three bent specimens experienced an identical damage level in low-to-medium-level seismic events. Notably, in high-intensity seismic conditions, B2-PGS transitioned into a more critical damage level compared to the other bents, while B2-PGT demonstrated superior performance.  
It has been shown that the proposed GSS-GCT connection is promising in improving the seismic performance of precast segmental two-column bents under high-level earthquakes. Future research work is still required to (1) establish an accurate and reliable numerical model for two-column bents using the GSS-GCT connection, (2) propose an analytical method for the load-displacement curve of precast segmental two-column bents, and (3) provide design suggestions for the geometry and reinforcing details of the grouted central tenon.  
Conceptualization, Z.L.; Methodology, S.Z. and G.L.; Validation, T.T. and W.Z.; Formal analysis, S.Z., G.L. and J.H.; Investigation, G.L. and W.Z.; Resources, Z.L.; Data curation, W.Z. and Z.L.; Writing--original draft, S.Z.; Writing--review & editing, T.T. and J.H.; Visualization, S.Z.; Supervision, T.T. and W.Z.; Project administration, W.Z. and Z.L.; Funding acquisition, Z.L. All authors have read and agreed to the published version of the manuscript.  
The project was sponsored by the National Key R&D Program of China (Grant No. 2019 YFE0119800), the Scientific Research Foundation for the High-level Personnel of Nanjing Institute of Technology (Grant No. YKJ201985), and the Nanjing Institute of Technology Industrial Economics and Innovation Management Research Institute Open Fund Project (Grant No. JGKB202004).  
Not applicable.