## 6 Conclusions  
This paper discusses the influence of cover thickness, compressive strength, chloride diffusion coefficient, and surface defects, as well as the micro-environment of concrete on the service life of the Jiaozhou Bay sea-crossing railway bridge. The temperature and relative humidity in the concrete and the loading applied onto the reinforced concrete were measured. For the reinforced concrete in the service environment of the bridge, the service life prediction model was revised according to suggestions by DuraCrete. The main durability parameters were determined based on DuraCrete guidelines and the measured results. Further, using the revised model, the reliability indexes of the service life of concrete with carbon reinforced bars and with corrosion-resistant reinforced bars were calculated. Based on the measured data and the analyses, as described in this paper, the conclusions are as follows:  
Figure 17: Reliability index calculated by the Monte-Carlo simulation for the platform concrete.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multirow{2}{*}{\(\gamma_{C_{or}}\) **(\%)**} & \multirow{2}{*}{\(\mathbf{C_{or}}\) **(\%)**} & \multirow{2}{*}{\(\mathbf{A_{C_{old}}}\) **(\%)**} & \multirow{2}{*}{\(\mathbf{\gamma_{C_{old}}}\) **(\%)**} & \multirow{2}{*}{\(\mathbf{\gamma_{C_{old}}}\) **(mm)**} & \multirow{2}{*  
1. According to the in situ measurements, the actual mean compressive strength of the concrete is higher than the designed value, while the maximum difference between the measured and designed cover thicknesses of the concrete piers is less than 15 mm. Due to the non-uniform vibration during concreting, there are defects on the concrete surface. Further, the temperature at the concrete surface varies with the atmospheric temperature. The applied load testing shows that the concrete structure suffers the effect of loading, which results in a larger chloride diffusion coefficient.  
2. According to the suggestions by DuraCrete, the model was revised by adding two parameters, i.e., the loading factor '\(k_{\text{s}}\)' and the temperature factor '\(k_{\text{t}}\)'. The added parameters affect the service life prediction; moreover, the revised prediction model was used in the service life predictions.  
3. The partial factor method and Monte-Carlo simulations were used to predict the service life and the reliability index. The results show that by comparing the concrete in the marine and land sections, the predicted remaining service life of the Jiaozhou Bay sea-crossing railway bridge can meet the designed 100 years, based on the revised DuraCrete model. Additionally, the reliability index calculations based on the Monte-Carlo simulations show that the results of the partial factor method are relatively reliable.  
Conceptualization, Z.J. and T.Z.; Formal analysis, Z.L.; Investigation, Z.L.; Methodology, Z.J. and T.Z.; Resources, Z.J. and T.Z.; Software, P.W.; Supervision, Z.J. and T.Z.; Writing-original draft, Z.L.; Writing-review and editing, Z.L., C.X., Y.K. and L.Z.; For other cases, all authors have contributed equally.  
Funding: National Key R&D Program of China Grant No. 2017 YFB0310000, Key Research and Development Program of Shandong Province No. 2019 GGX102053, National Natural Science Foundation of China (NSF) Grant No. 51678318, 51709253, 51420105015 and 51608286, Chinese National 973 projects Grant No. 2015 CB655100, 111 Project and Chinese Scholarship Council (CSC).  
The authors declare no conflict of interest.