## 4 Conclusions  
This paper presented a fatigue performance evaluation of the cable-girder anchorage zone of the Heilongjiang Bridge. As this bridge is located in the northernmost region of China, with the lowest service temperature of \(-44.5\)\({}^{\circ}\)C, the influence of low temperature was examined in terms of fatigue load effect and fatigue resistance. Combining a room temperature fatigue test with a numerical analysis of the crack growth pattern and crack propagation life, a fatigue assessment of the anchorage structure at low temperatures was conducted. The following conclusions were drawn:  
1. A room temperature fatigue test loaded up to 3.2 million cycles was performed on a 1:3.75 scale specimen of the most stressed anchor box B17. After 2 million cycles of design cable force loading that took the low-temperature load effect into account (load range of 135 kN in the specimen, representing 1905 kN in the actual bridge), and after an additional 1.2 million cycles of incremental loading up to twice of the design cable force, no crack was found in the anchor box and adjacent plates.
2. An extended finite element method was adopted to analyze the crack initiation location and crack propagation path of the anchorage structure. A fatigue crack is most likely to appear in the outer girder web at the anchor end of its connection with the upper support plate. As illustrated in Figure 15, it probably will propagate to both sides along the direction that is perpendicular to the support plate and be arrested by the web stiffeners.
3. Based on the characteristic fatigue parameters of bridge steel at low temperatures, the resistance of an anchorage structure to fatigue crack propagation in a low ambient temperature environment was evaluated. Although the resistance of the anchorage structure to fatigue crack instability decreases and fractural critical crack size \(a_{\mathit{cf}}\) is reduced to 1/4 of that at room temperature, the risk of a brittle fracture at low temperature is small with the \(a_{\mathit{cf}}\) as large as 1.875 m. The fatigue crack propagation life of an anchorage structure at low temperature is 1.6 times that at room temperature thanks to a slower crack growth rate. Nevertheless, tough structural steel and anchor box structures with a smooth transition of geometries are recommended to further safeguard the cable-girder anchorage zone in a low ambient temperature environment.  
Conceptualization, H.C. and W.B.; methodology, H.C. and Y.J.; software, Y.Z.; validation, H.C., W.B. and Y.J.; formal analysis, Y.Z. and H.C.; investigation, H.C. and Y.Z.; resources, H.C., W.B. and Y.J.; data curation, Y.Z.; writing--original draft preparation, H.C.; writing--review and editing, H.C., Y.Z., Y.J. and W.B.; visualization, Y.Z.; supervision, H.C.; project administration, H.C.; funding acquisition, H.C. and W.B. All authors have read and agreed to the published version of the manuscript.  
This research was funded by NATIONAL NATURAL SCIENCE FOUNDATION OF CHINA, grant number 51008006, 52278137. The APC was funded by the open access program of Beijing University of Technology.  
Not applicable.  
Details of the experimental data and the analytical model presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
**Acknowledgments:** The authors appreciate the help from graduate students ([PERSON], [PERSON], [PERSON], [PERSON], [PERSON]) and technical staff ([PERSON], [PERSON]) during fatigue testing. Bridge technical documentation from Heilongjiang Bridge Engineering Management Co., Ltd. and the China Communications Construction Co., Ltd. is also acknowledged.  
**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.