## 5 Conclusions  
Experimental pseudo-static low-cycle tests on the girder-integral abutment-RC pile-soil system revealed the following aspects within the limitations of this paper, as follows:  
* The failure modes of the girder-integral abutment-pile system with or without the girder were different. For the integral abutment-pile system, only the piles were severely damaged, and no damage could be found to the abutments. For the girder-integral abutment-pile system, the piles were damaged at the beginning and then the abutments were also damaged under a large horizontal displacement. Compared to the system without the girder, the horizontal displacement corresponding to the first crack on the pile of the girder-integral abutment-pile system was larger, and  
Figure 15: Improved secant stiffness degradation curve. the damage to the pile was less severe, which is beneficial to the piles. The damage to the abutments in the girder-integral abutment-pile system should attract attention;
* Compared to the system without a girder, reductions of 39.2%, 22.6%, and 12.6% in the initial stiffness under positive horizontal displacement, residual force accumulation, and residual deformation were observed in the girder-integral abutment-pile system, respectively. Increments of 112.6%, 67.2%, 30.8%, 20.4%, and 7.8% in the initial stiffness under negative horizontal displacement, displacement ductility ratio, average equivalent viscous damping ratio, yield load, and ultimate load were observed in the girder-integral abutment-pile system, respectively;
* Compared to the system without the girder, a smaller elastoplastic stage range and a larger elastic stage range of the skeleton curve, as well as less reduction in the stiffness, were observed in the girder-integral abutment-pile system;
* To accurately reflect the seismic performance of a girder-integral abutment-RC pile-soil system, it is suggested to consider the girder. When the girder was considered, the resistance of the girder-integral abutment-RC pile-soil system against earthquakes increased because of the increased energy dissipation capacity and displacement ductility, as well as the decreased stiffness degradation. Moreover, the failure mode of the specimen changed from severe damage to the pile top under a small displacement to damage to both the abutment and pile top under a large displacement. From a practical point of view, the repair of abutments is easier than that of piles. This research serves as a basis for more in-depth investigations into the performance of girder-integral abutment-pile-soil systems in IABs. In future research, the influence of different parameters on the seismic performance of the girder-integral abutment-pile-soil system will be investigated in detail through experimental tests. Conceptualization, B.B., J.X. and C.N. ; methodology, W.G., B.B., J.X. and C.N. ; validation, W.G., B.B., J.X. and C.N. ; formal analysis, W.G. and [PERSON]; investigation, [PERSON]; resources, [PERSON]; data curation, [PERSON] and [PERSON]; writing--original draft preparation, [PERSON]; writing--review and editing, [PERSON], [PERSON], [PERSON], C.N. and F.H. ; visualization, [PERSON]; supervision, [PERSON], J.X. and C.N. ; project administration, [PERSON]; funding acquisition, [PERSON] and J.X. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China (51778148); the National Natural Science Foundation of China (51508103); the Recruitment Program of Global Experts Foundation (TM2012-27); the 2023 Fujian Provincial Transportation Science and Technology Demonstration Project (SF20230202); the Open Project Fund of the Sustainable and Innovative Bridge Engineering Research Center of Fujian Province University (Grant No. SIBERC 202203); and the Open Project of Fujian Provincial Key Laboratory on Multi-Disasters Prevention and Mitigation in Civil Engineering (MPMC-2022-4). Not applicable.