An Experimental Study on the Equivalent Load Effect of Bridge Scour

An Experimental Study on the Equivalent Load Effect of Bridge Scour

In recent times, scour has become the major cause of failure for cross-water bridges owing to frequently occurring hydraulic hazards such as typhoon-induced flood. Although the scour phenomenon has been studied for a long time by hydraulic researchers, its effect on a bridge structure has still not been clarified sufficiently for use in engineering design. Although current bridge design does consider the scour effect for bridge safety, it is merely used to verify stability under scour and is not actually a design factor that influences bridge structure design. This is because the result of scour is not an additional external force but a reduction in resistance. This paper discusses an innovative idea that transforms the reduction in the soil bearing capacity of the bridge pier foundation into a load effect on the structure. In order to verify the proposed method for evaluating the reduction in soil bearing capacity that comes with decreasing embedded depth of the pile, a series of lateral bearing capacity tests were conducted with a model pier under controlled conditions to establish the relationship between the scour depth and the soil bearing capacity of the pier model. This study verifies the proposed methodology used for converting the scour depth, the soil bearing capacity reduction, into the equivalent scour load. When the expected scour depth is known, the calculated corresponding equivalent scour load can be used to design a bridge structure with suitable lateral loading capacity. In order to more generally apply the equivalent scour load to design specifications, the scale effect of the bridge pier should be further investigated.