## 9 Conclusions  
This paper has presented the fatigue life assessment of a typical steel high-rise steel braced frame structure using the equivalent structural stress method. By establishing multi-scale FE model and time-history analysis, fatigue assessment is performed using equivalent structural stress method. As a result, Location 1, which is lateral weld toe of the butt weld connecting the upper beam flange plate and column, is found to be the most dangerous location and is likely subjected to fatigue damage. This can provide reference to the design of steel high-rise steel braced frame structures. Furthermore, the comparison of the results obtained by equivalent structural stress and hot spot stress show fatigue damage calculated by equivalent structural stress is higher, which means the fatigue assessment by  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Method** & **Location** & \(D_{50 nom}\) & \(D_{annualnom}\) & \(T_{nom}\)/Year** \\ \hline Nominal stress & Global & \(1.377\times 10^{-10}\) & 4.342 \(\times 10^{-5}\) & 2.3 \(\times 10^{4}\) \\ Equivalent & Location 1 & \(5.986\times 10^{-9}\) & 0.0038 & 265 \\ structural stress & Location 4 & 7.887 \(\times 10^{-16}\) & 4.974 \(\times 10^{-10}\) & 2.010 \(\times 10^{9}\) \\ \hline \hline \end{tabular}
\end{table}
Table 8: Fatigue assessment using different methods.  
equivalent structural stress method is more conservative and tends to be safer. Meanwhile, the results based on nominal stress reflects that nominal stress method considers the weld in a more global way, which averages all the stress on the weld plate section and cannot take into account the local stress concentration near the welds accurately. However, in nominal stress assessment, only global FE model is required and the computing time is much shorter than that in equivalent structural stress or hot spot stress. Therefore, nominal stress method, hot spot stress method and equivalent structural stress method have their own advantages and disadvantages and selection needs to be determined according to detailed circumstances. Generally speaking, in fatigue assessment of large-scale complex structures, nominal stress method is recommended to be used to study the fatigue damage trend, and is especially suitable for looking for the critical components regarding fatigue failure in large-scale structures. Equivalent structural stress method or hot spot stress method if the conditions are allowed (computing resources and time are abundant) is recommended to be used to analyze the fatigue life accurately. Furthermore, the methodology stated in this paper can be applied similarly to any high-rise steel structure, including mast structures and tower structures with welded joints, thus providing reference to wind-induced fatigue assessment of any high-rise steel structure.  
The authors would like to gratefully acknowledge the financial support for this work from the National Natural Science Foundation of China (No. 51438002, No. 51278104 and No. 51568041) and China Postdoctoral Science Foundation (No. 2015M571641).  
All authors discussed and agreed on the idea and scientific contribution. [PERSON] did the mathematical modeling, performed the simulations and contributed to the writing. [PERSON], [PERSON] and [PERSON] contributed to the revisions and discussion of the results.  
The authors declare no conflict of interest.