Influence of scour effects on the seismic response of reinforced concrete bridges

Flood-induced scour is a common phenomenon that causes the loss of lateral support at bridge foundations. However, the impact of scour is usually ignored when assessing the anticipated response of bridges under earthquake loads. This study quantifies the effect of scour on the dynamic behavior and seismic performance of reinforced concrete (RC) bridges. Additionally, this study investigates potential structural design alternatives to mitigate damage from earthquake exposure given scour conditions. Since the structural periods corresponding to the first few vibration modes increase with the increase of scour depth, this study finds that the sensitivity of the periods to the scour depth varies for different types of bridges. Also, bridge variety determines whether scour has a beneficial or detrimental effect on the seismic column fragility. In addition, scour may amplify the potential seismic damage of the bridge via transferring damage from the column to the pile foundations, or increasing the probability of deck unseating. Regarding strategies to manage detrimental scour effects, this study finds that increasing the foundation stiffness is effective for reducing the seismic damage of scoured bridges, while increasing the foundation depth only has a minor effect. Also, the foundation type has great impact on the seismic performance of scoured bridges. The findings of this study can be used to guide the seismic design of new bridges or the retrofit of existing bridges in transportation networks along flood-prone regions.