چكيده به لاتين
Bridges are among the most important and vital structures in each country. Due to the special function of the bridges, as well as the many financial and human problems in the event of damage, it is essential that the performance of the bridges, especially the bridges' seismic performance, against structural deterioration factors such as chloride-induced corrosion, carbonation and alkaline reaction of aggregates must be examined.
The chloride-induced corrosion and its effects on bridges' vulnerability is one of the newest issues in structural engineering that has attracted more researchers. Chloride-induced corrosion reduces the durability of concrete bridges and damages concrete pillars, making it more vulnerable to earthquakes. The performance of chloride ion is that in the presence of moisture, penetrates the concrete through concrete pores and, due to the diffusion and propagation phenomena, increases its concentration in concrete, especially in the concrete and reinforcement boundaries. By passing the chloride concentration from a critical value near the concrete reinforcement surface, the inactive layer around the reinforcement is damaged and if there is enough oxygen at the boundary of the armature, corrosion reactions begin. The volume of these corrosion products produced is greater than the volume of steel and causes pressure on the concrete around the rebar. This pressure on the concrete around the rebar will crack the concrete and reduce the mechanical properties of the concrete and the reinforcement.
In this research, a horizontally curved concrete bridge, which is one of the most common and most vulnerable bridges, is firstly modeled without corrosion, and then the seismic response of the bridge is presented in terms of fragility curves. Corrosion has been modeled according to the mechanical characteristics of the reinforcing bars and concrete in different years and the seismic response of the bridge is presented in terms of fragility curves. Subsequently, these fragility curves are compared and analyzed in different limit states. According to the results of this research, at the level of low, moderate, extensive and complete damage state, respectively, we saw a decrease of 15.46%, 8.39%, 12.42% and 8.52% in the mean values of the fragility of the seismic response of the columns after 75 years of life
