Time-Dependent Seismic Assessment of Typical Highway Bridges Subjected to Corrosion in Persian Gulf Zone

In high seismic regions, such as Persian Gulf zone in Iran, corrosion of reinforcement and concrete deterioration can affect the seismic capacity of the structures and increase the vulnerability to the future seismic events. Although corrosion of reinforcement has the potential to affect all types of reinforced concrete structures, the highway bridges are vulnerable to more damage because of deicing salts, water splash or even seawater during their life cycle. The long-term corrosion process of a deteriorated typical RC highway bridge in Iran is analyzed as a function of time by using nonlinear static and dynamic analyses for seven earthquake ground motion records at three levels of intensity (0.3g, 0.5g and 0.75g). Three combined effects of corrosion (the loss of the cross sectional area of the reinforcement bars, decrease of the capacity of corroded reinforcing bars, and stiffness degradation of concrete cover resulting from reinforcement corrosion) were used in the time-dependent nonlinear analyses for six different time steps (i.e., non-corroded (t: 0), 10, 20, 30, 40, and 50 years) after corrosion initiation time. The results show that removing the concrete cover on bottom of columns has a greater impact on the structural capacity of the RC bridge than decreasing the rebar mechanical parameters.