## 6 Conclusions  
Aiming at the optimization of the traffic load model of super-long-span suspension bridges, this paper carried out related studies specific to suspenders of a suspension bridge with a main span of 2300 m, and the main conclusions are drawn as follows:  
(1) There are a large number of suspenders of super-long-span suspension bridges, and the suspenders are mainly sensitive to the heavy concentrated forces acting in the vicinity of them. Different suspenders have different safety margins under the action of the same level of traffic load. When the actual traffic load is heavy, the other main components designed according to the specification can ensure reasonable service safety, but the load effect of some suspenders may exceed the limit. (2) The influence lines of the axial force of suspenders can be classified according to their geometric features. According to the quantity and sign of extreme points, all of the influence lines of the axial force of suspenders were classified into three categories, namely the Inverted icicle type, the Angle iron type, and the W-shape type, and each type represents the different position information and mechanical characteristics of suspenders. (3) By generating random traffic flow data and analyzing the contained vehicle distribution and vehicle weight information, scenarios that could induce an extreme traffic load effect were extracted, and a corresponding load model was built according to the \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{3}{*}{**Suspender**} & \multicolumn{3}{c}{**Uniformly Distributed Load (kN/m)**} & \multicolumn{3}{c}{**Concentrated Force (kN)**} \\ \cline{2-7}  & **Optimized Model** & \begin{tabular}{c} **Extreme Load** \\ **Effect Scenario** \\ **Model** \\ \end{tabular} & \begin{tabular}{c} **Specification Model** \\ **Model** \\ \end{tabular} & \begin{tabular}{c} **Optimized Model** \\ \end{tabular} & \
\begin{tabular}{c} **Extreme Load** \\ **Effect Scenario Model** \\ \end{tabular} &
\begin{tabular}{c} **Specification Model** \\ \end{tabular} \\ \hline HMM & 6.4 & 4.5 & & 1433 & 1277 & \\ HSL & 8.9 & 3.0 & 10.5 & 1314 & 1161 & 360 \\ HSS & 7.7 & 7.0 & & 1426 & 1408 & \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Comparison of load model values. Figure 9: Comparison of traffic load effect of suspenders—growth rate (%). calculation results of the load effect. The load value of this model was used as a reference to establish an optimized traffic load model. (4) Multi-objective optimization based on genetic algorithm was adopted to optimize the traffic load model of suspenders, and three representative suspenders were selected for case study. Taking accuracy, convenience, and improvement as the optimization objectives, the optimized traffic load models corresponding to each representative suspender were built. In terms of the load value, compared with the specification model, the uniformly distributed load of the optimized model decreased from 1.6 kN/m to 4.1 kN/m, and the concentrated force increased significantly, which could reach four times that of the specification model at most. In terms of load effects, the optimized model can well envelope the extreme load effects of suspenders that may occur during the design reference period, and the safety margin for the extreme load effect accords with the mechanical characteristics and load effect levels of each suspender, which proves that the optimized model has a reasonable optimization result. Although the issue of the loading length of uniformly distributed load has been analyzed, the conclusions drawn in this paper are mainly focused on the valuing of the traffic load model and its reasonable safety margin. Possible changes to the calculation scheme and fineness of the load model can be further discussed in future studies. In addition to the static effect, the dynamic response induced by heavy vehicles is also of great significance for the resistance performance of suspension bridges.