# Seismic Study of An Isolated Cable-Stayed Bridge under Near-Fault Ground Motions
## 6 Conclusions  
This paper primarily focuses on the study of bounding performance at the expansion joints between the main cable-stayed bridge and the approach bridge, an aspect that has been rarely addressed in previous research. The application of friction pendulum bearings (FPBs) and fluid viscous dampers (FVDs) to mitigate bounding effects is investigated. Furthermore, a detailed analysis of the bounding effects on cable-stayed bridges equipped with FPBs and FVDs is conducted, considering the influences of traveling wave effects, input seismic wave types, and soil types. Based on the analysis results, the following conclusions are drawn:  
(1) Pounding effects between the main bridge and the approach bridge will exacerbate the deformation of the approach bridge and need careful consideration. Although the bounding effect increases the bearing deformation for both the prototype bridge and the isolated bridge, the degree of increase is different. The impact of bounding on the prototype bridge is greater than that on the isolated bridge. The installation of FPBs and FVDs can significantly reduce bounding forces and their associated risks.  
(2) For cable-stayed bridges equipped with FPBs and FVDs, traveling wave effects alter the peak values, frequencies, and timing of bounding forces. As the seismic wave velocity decreases, the asynchronous movement on both sides of the bridge becomes more pronounced, increasing the risk and harm of poundings.  
(3) Compared to far-fault seismic motions, near-fault seismic motions result in more significant seismic responses and higher bounding probabilities for cable-stayed bridges with FPBs and FVDs. In the current study, FPBs and FVDs help prevent pounding under far-fault motions, but poundings can occur when considering near-fault excitations.  
(4) The type of soil has a relatively small impact on pounding forces but should not be overlooked regarding its influence on bearing deformations and tower internal forces. Soft soil can extend the natural period of vibration for large-span cable-stayed bridges, reduce the overall system stiffness, and consequently decrease bearing deformations and bending moments in the bridge towers.  
Conceptualization, H.G., Z.D. and L.Z.; methodology, H.G., L.L. and L.Z.; software, H.G., Z.D. and K.Z.; validation, K.Z. and Z.D.; formal analysis, H.G. and L.L.; investigation, Z.D. and L.Z.; resources, L.Z.; data curation, H.G and Z.D.; writing--original draft preparation, H.G.; writing--review and editing, K.Z., L.L., Z.L., Z.D. and L.Z.; visualization, H.G., L.L. and L.Z.; supervision, L.L., Z.L. and L.Z.; project administration, L.Z.; funding acquisition, L.Z. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was supported by National Key Research and Development Program of China: 2022 YFC3801100 and The National Natural Science Foundation of China: 52378147.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
**Conflicts of Interest:** [PERSON] was employed by the company China Construction Eighth Bureau General Contracting Construction Co., Ltd. [PERSON] was employed by the company. MCC5 Group Shanghai Corp., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.