**5. Conclusions**

A 1:10 scale model test was conducted based on the Tian'e Longtan Grand Bridge with a main span of 600 m. Considering the shortcomings of traditional loading methods in the test design process, an array-type, self-balancing pulley-group loading system was designed. This system was introduced, tested, optimized, and compared with the finite element simulation calculations. The main conclusions are as follows:


slightly higher than that of the original bridge due to the increased self-weight load caused by the increase in the thickness of the model bridge's web from the design value of 45 mm to 55 mm. At other key construction stages, the maximum relative errors in the stress results of the rigid steel frame and the concrete inside the pipe for the two bridges are 8.33% and 9.34%, respectively. The maximum absolute error of the bottom plate concrete is 0.66 MPa, verifying the correctness of the counterweight optimization algorithm of the array-type, self-balancing pulley-group loading system.

It is worth mentioning that the loading point of this experiment considered the position of the columns on the original bridge arch, which can meet the simulation loading requirements of the arch structure. Considering the long-term behavior and failure mode of the structure under full bridge load, it will be the next research direction.

**Author Contributions:** Conceptualization, Y.F. and J.Z.; methodology, Y.F. and C.L.; software, Y.F.; validation, J.X., J.Y. and S.W.; formal analysis, Y.F.; investigation, J.Z.; resources, C.L.; data curation, J.X.; writing—original draft preparation, J.Y.; writing—review and editing, S.W.; visualization, Y.F.; supervision, J.Y.; project administration, J.X.; funding acquisition, J.Z. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by Science and Technology Project of Chongqing Municipal Transportation Bureau (Grant No. KJXM2021-0966); Guangxi key research and development plan project (Grant No. GuikeAB22036007); Independent research and development project of the State Key Laboratory of Mountain Bridge and Tunnel Engineering (Grant No. SKLBT-YF2103); Project of Science and Technology Program of Department of Transport, Hubei Province (Grant No. 2020-186-1-6) and Chongqing Jiaotong University Postgraduate Scientific Research Innovation Project (Grant No. CYB22232).

**Data Availability Statement:** The data presented in this study are available from the first and corresponding author upon request. The data are not publicly available due to the policy of the data provider.

**Conflicts of Interest:** The authors declare no conflict of interest. The sponsors had no role in the design, execution, interpretation, or writing of the study.

#### **References**


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**Dan Ye 1,2,\*, Yijin Tong 1, Lijun Gan 1, Zhuoran Tang <sup>1</sup> and Ruijie Zhang <sup>1</sup>**


**Abstract:** The applicability of current seismic-performance-improvement technologies needs to be studied. This research took a super-long-span CFST arch bridge with a total length of 788 m as the object on which to perform a non-linear time-history analysis and a seismic-check calculation according to the seismic response, so as to reveal the seismic weak points of the arch bridge. After the completion of the bridge's construction, we arranged and utilized the stayed buckle cables (SBCs) reasonably. The seismic performance of the super-long-span CFST arch bridge was improved through friction-pendulum bearings (FPBs) and SBCs. The research shows that FPBs can solve the problem of the insufficient shear resistance of bearings, and SBCs can address the problem whereby the compressive stress of the transverse connection of the main arch exceeds the allowable stress. Moreover, SBCs can increase the transverse stiffness of arch bridges and reduce their seismic responses. Finally, a combination of FPBs and SBCs was adopted to improve the overall seismic performance of the arch bridge and obtain the best seismic-performance-improvement effect.

**Keywords:** CFST arch bridge; super-long span; friction-pendulum bearing; stayed-buckle cable; seismic-performance improvement
