## 1 Introduction  
In recent years, with the rapid development of urbanization and transportation networks, long-span suspension bridges have become an important choice to address the traffic bottleneck problems in the road network. In particular, those suspension bridges whose main span reaches 2000 m are often faced with the dual challenges of technological innovation and construction costs. As a key engineering structure, suspension bridges require the continuous improvement of their design. In order to meet the growing traffic demand and optimize the performance and economic benefits of suspension bridges, the development of a technical standard needs ongoing innovation and effective progress. With the in-depth study of structural performance and traffic load, the need to adjust the traffic load standard according to the design characteristics of bridges to meet the needs of structural performance and traffic network function has become a consensus. This initiative not only helps to improve the safety and reliability of the suspension bridge, but also provides strong support for the development of transportation infrastructure. Being one of the main load-bearing components of a suspension bridge, the mechanical performance of a suspender is crucial to the structural integrity and service safety of the bridge. By connecting the main cable and the deck, the suspender converts the tension of the main cable into the supporting force for the bridge deck, ensuring the stability and safety of the whole structure. Compared with the mechanical characteristics of the main cable, main beam, main tower, and other components, the load response of the suspender is localized, that is, the suspender is most sensitive to the load action within a certain range nearby, while the load action outside of this range will hardly have any obvious impact on it. In addition, through the investigation of existing studies, it has been found that, under the same level of traffic load, the load effect level of a suspender is higher than that of the other main components, and the effect beyond the limit value is more likely to occur [1; 2], resulting in the elevated overall stress of the suspender and the bridge. Therefore, it is urgent and of practical significance to study the extreme effect of traffic loads on suspenders and to establish a corresponding load model. At present, the research on the modeling of traffic load mainly focuses on common issues, including the statistical analysis of load parameters, load modes and their values, load combinations, and partial safety factors, etc., [3; 4; 5; 6; 7; 8]; however, there are still few studies of particular issues related to traffic load, such as the extreme load effect scenarios, differences among the responses of the main components to traffic load, and the reasonable traffic load determination for super-long-span suspension bridges. The uncertainty of traffic load and its effect is mainly caused by its complex temporal and spatial distribution. If the most unfavorable traffic load effect of the components cannot be calculated accurately, it will be difficult for the bridge design, management, and maintenance parties to obtain specific operational decision-making guidance, which is harmful to the safe service of the components and the overall structure. Therefore, based on the above shortcomings in the analysis of the suspender load effect and the construction of the traffic load model, it is necessary to optimize and improve the existing traffic load model. To optimize the traffic load model of a suspender, it is important to determine an appropriate optimization objective and select a suitable optimization algorithm. In the engineering field, several aspects regarding the traffic load model are of great concern, including the accuracy of the load effect analysis, the complexity of the calculation process, and the rationality of the calculation scheme.