دانلود رایگان مقاله انگلیسی قابلیت اطمینان سازه های بتن آرمه در معرض خوردگی و تغییرات اقلیمی - اشپرینگر 2018

Abstract

Durability of reinforced concrete (RC) structures is affected by certain environmental conditions and operational actions which can reduce their lifetime significantly. Among these actions, this paper proposes a stochastic model that accounts for the combined effects of chloride-induced corrosion, climate change and cyclic loading. Separately, corrosion leads to cross-section reduction, climate change produces changes in temperature and humidity and fatigue induces nucleation and propagation of cracks in the rebars. When considered together, pitting corrosion nucleates cracks while environmental factors affect the kinematics of chloride ingress and corrosion propagation. The proposed approach is illustrated with the reliability analysis of a bridge girder subjected to cyclic loading under various environmental conditions. The overall results indicate that climate change effect induces lifetime reductions ranging between 1.4 and 2.3% if fatigue load is neglected. Under cyclic loading, total lifetime reduction increases up to 7%.

6. Conclusions

This paper presented a deterioration model that integrates the effects of chloride-induced corrosion, climate change and cyclic loading for RC structures. The total corrosion-fatigue life was divided into three stages: (i) corrosion initiation and pit nucleation, (ii) corrosion initiation and pit nucleation, and (iii) crack growth. Since some of these stages are sensitive to climatic conditions, a simplified model of weather that includes global warming was also included. The whole deterioration model was introduced into a stochastic framework to take the inherent uncertainties into account. Finally, a numerical example illustrated the consequences of the deterioration process in the reliability of a RC bridge girder. It was found that for traffic frequencies between 500 and 2000 cycles/day, the combined effect of corrosion and fatigue leads to appreciable lifetime reductions. When no fatigue damage is considered, the climate change effect only induces lifetime reductions ranging between 1.4 and 2.3%. Under cyclic loading, total lifetime could be reduced up to 7% by global warming action. These results highlight the importance of including the combined effect of corrosion and fatigue for comprehensive lifetime assessment.