# Climate Change Impact on Corrosion of Reinforced Concrete Bridges and Their Seismic Performance
## 5 Conclusions  
In this paper a procedure for the assessment of the seismic performance of an existing RC viaduct located in the Massa-Carrara province, when subjected to different corrosion scenarios and considering the age of the structure. In particular, the impact of global warming on the evolution of corrosion phenomena due to carbonation is discussed, considering available climate projections and future emission scenarios. Three different corrosion levels were investigated: (i) slight, (ii) moderate, and (iii) high; these were characterized by different values of mean corrosion current density (\(i_{corr}\)). Moreover, the values of \(i_{corr}\) obtained from the DuraCrete research work were considered, in order to evaluate the difference between these values and those obtained using the climate change impact model prediction. To assess the seismic vulnerability of the viaduct, an efficient methodology, based on the implementation of simplified 3D finite element models, was used, taking into account ductile and brittle failure mechanisms. The analyses were carried out using different time steps: at the time of construction of the viaduct and after 13.5, 50, 75 and 100 years of its service life. This was undertaken in order to look at the evolution of the effects of corrosion as a function of the age of the structure, expressed in terms of the reduction in longitudinal and transverse steel reinforcement area by means of an analytical model. The results obtained are reported using appropriate risk indices, defined as the ratio between the peak ground acceleration, which leads to the collapse of the first monitored pier (\(PGA_{C}\)), and the design peak ground acceleration (\(PGA_{D}\)), calculated as reported in the Italian Design Code, and as the ratio of the related return periods (\(RP_{C}\) and \(RP_{D}\)). The following points can be observed from the obtained results:  
* The values of \(i_{corr}\) calculated considering the climate change impact through the indications suggested by [PERSON] et al. are lower than those obtained considering the results reported in DuraCrete, except for the slight corrosion scenario, which does not significantly influence the seismic performance of the viaduct;
* The corrosion effects, expressed in terms of the reduction in steel reinforcement, influence the brittle failure mechanism more significantly than the ductile one;
* Considering the corrosion scenarios obtained from the above-mentioned climate change impact prediction model, a significant reduction in the risk indices, which characterize the seismic vulnerability of the viaduct, are observed only for the high corrosion level (\(i_{corr}=0.431\)\(\mu\)A/cm\({}^{2}\)) with the brittle collapse mechanism;
* Different conclusions can be observed when considering the \(i_{corr}\) values proposed by DuraCrete, where an important decrease in risk index values is obtained for the moderate and high corrosion scenarios. Focusing on the high corrosion level, the reduction in the risk index values exceeds 90% for the brittle collapse mechanism and 80% for the ductile collapse mechanism;
* The corrosion levels obtained from DuraCrete lead to more critical scenarios compared to those obtained from climate change projections for the area where the analyzed viaduct was built, when the corrosion rates proposed by [PERSON] et al. are considered. Finally, it is important to highlight that the comparison of the results obtained, considering the different scenarios analyzed, is useful to improve the maintenance and management of these strategic structures, in order to always guarantee an adequate safety level. Potential future developments of this research work are related to the generalization of the results obtained, by considering other viaducts built in different years and located in different seismic zones. Conceptualization, M.Z. and F.L. ; methodology, M.Z., M.L.P., F.L., F.M., P.F. and P.C. ; validation, F.M., P.F. and P.C. ; formal analysis, M.Z. and M.L.P. ; investigation, F.L. ; editing, F.L., F.M., P.F. and P.C.