ABSTRACT
Floods can have devastating effects on bridges. They occur in most geographical regions, and their effects are felt by the structural system of the bridge, as well as the supporting soil and the approaching streams. Floods can affect the bridge system in five distinct ways as shown in Figure 1.1. Overtopping happens when the floodwater level becomes higher than the bridge superstructure and can lead to major bridge damage (Figure 1.2). Debris carried by floodwaters can impact the bridge structure and cause damage in the process (Figures 1.3 and 1.4). Harmful effects of the debris from hurricanes can be seen in Figure 1.4. Direct water pressure can affect the bridge and cause structural failure. Another form of flood effect is the potential failure of embankments, which in turn can damage the bridge. Finally, floodwater and stream flow can cause soil erosion, either under the foundation of the bridge or near the approaches to the bridge. This process is called “scour.” Scour effects account for most failures due to floods (Table 1.1). The five modes of flood damage to bridges are summarized in Table 1.2.
