Stability Analyses of Cross-river Bridges under Flood Water and Debris Loads(III)

Stability Analyses of Cross-river Bridges under Flood Water and Debris Loads(III)

The purpose of the present study was to investigate the stability of cross-river bridges subject to hydraulic loads and debris accumulation during extreme flood events. According to past reconnaissance reports on typhoons and floods, the collapse of many bridges can be attributed to debris accumulation. The debris not only increases the effective area of the substructure components, but also reduces the flow area resulting in backwater upstream and increased velocities flowing through the bridge opening. The effect of debris accumulation, however, is not included in the current bridge design code in Taiwan. In order to gain a better understanding of bridge behavior in an extreme flood event, the hydraulic loads have to be calculated precisely, especially the hydraulic loads under the condition of debris accumulation. Therefore, a series of small scale hydraulic model tests for a single pier and large scale hydraulic model tests for a continuous bridge under floodwater and debris loads were conducted.