## 6 Conclusions  
In the present study, the time-dependent fatigue reliability of the suspenders considering life time stochastic wind and traffic loads was evaluated based on fully coupled traffic-bridge-wind (TBW) analysis. In order to accurately predict the fatigue reliability of the suspenders, the in-situ monitoring data containing the essential wind and traffic information were analyzed thoroughly first and then subsequently implemented into the stochastic wind and traffic model. Finally, the linear fatigue damage rule was adopted to estimate the fatigue life of the suspenders. The following conclusions could be drawn:  
1. If only the wind load is considered, the results indicate that high wind speeds could cause much more significant fatigue damage on the suspenders than low wind speeds.
2. If only the traffic load is considered, it was found that the stress level of the stress response of the suspenders under free-flow traffic is at the same level as that under busy-flow traffic. However, the variation frequency of the stress response of suspenders is lower than that under busy-flow traffic, especially for short suspenders S19 and S36.
3. Considering both wind and traffic loads, it was indicated by the stress responses of the suspenders that both wind and traffic play significant roles in predicting the fatigue life of suspenders.
4. The short suspender S36 (mid-span suspender) and the long suspender S2 (girder end suspender) were, respectively, the suspenders most and the least prone to fatigue damage. In addition, provided with a target reliability index of 3.0 and considering the lifetime wind and traffic load, the fatigue life of suspenders S36 and S2 was estimated at 53 years and 167 years, respectively.  
In the present study, only the portion of the suspender away from the structural connections, e.g., anchor zone, was investigated. The portion of the suspender near or located at the structural connections is subjected to very complex stress status including tension, bending, or even shear and torsion. Under such complex stress status, a more sophisticated methodology, e.g., fracture mechanics probably combined with very refined finite element modeling, may be required to evaluate the fatigue damage and predict the fatigue life of the suspender, which is currently under investigation by the authors.  
Conceptualization, M.W. and J.Z.; methodology, M.W.; software, M.W.; validation, M.W. and J.Z.; formal analysis, M.W. and J.Z.; investigation, M.W.; resources, M.W. and J.Z.; data curation, M.W.; writing--original draft preparation, M.W.; writing--review and editing, J.Z., J.H. and S.K.; visualization, J.Z. and J.H.; supervision, J.Z. and S.K.; project administration, J.Z.; funding acquisition, M.W.  
This material is based on the work supported by the National Natural Science Foundation of China (No. 51708470, 51908472, 51608193), the Young Scholars Development Fund of SWPU (No. 201699010111), the China Postdoctoral Science Foundation (No. 2019 TQ0271), the Scientific Research Starting Project of SWPU (No. 2017 QHZ025), the Scientific Innovation Group for Youths of Bridge Safety Evaluation of SWPU (No. 2018 CXTD07), and the Scientific Innovation Group for Youths of Sichuan Province (No. 2019 JDTD0017). These supports are greatly appreciated. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsors.  
Figure 11: Fatigue reliability index of the four representative suspenders.  
**Acknowledgments:** The third author gratefully acknowledges financial support from China Scholarship Council and British Council during studying in the UK.  
**Conflicts of Interest:** The authors declare no conflict of interest.