Lifetime seismic resilience assessment of a sea-crossing cable-stayed bridge exposed to long-term scour and corrosion

In the marine environment, bridges are exposed to long-term foundation scour and structural corrosion. Consideration of scour and corrosion effects is of crucial importance for the lifetime seismic resilience assessment of existing sea-crossing bridges. This study presented a framework of seismic resilience assessment for seacrossing bridges exposed to long-term scour and corrosion. Three typical recovery functions were employed to establish the post-earthquake functionality recovery model considering underwater repair. The time-variant model of scour depth was developed by fitting the annual measured data with the empirical function. The time-variant corrosion model induced by chloride was developed by considering different exposure zones. Then, the models of scour depth and corrosion were applied to an example cable-stayed bridge to assess the lifetime fragility and resilience of the bridge. It is concluded that the developed scour depth model agrees well with the measured data and can reasonably estimate the time-variant scour depth. Compared to scour, corrosion dominates the increase in lifetime fragility and resilience loss for the bridge. Scour and corrosion effects significantly reduce the bridge's functionality and increase the difficulty of the recovery process. Ignoring the effects of scour and corrosion can lead to an overestimation of the seismic resilience of the bridge.