Using a Curved Bed Sill as a Scour Countermeasure around a Complex Bridge Pier

Bridges are constructed to facilitate transport between riverbanks. These bridges are supported by piers of varying geometric shapes that differ from one bridge to another. The interaction between these piers and the flowing water generates different types of vortices, forming a scour hole around the piers. This local scour around the foundation of bridge piers is a major cause of bridge failure. This study experimentally investigated using a curved bed sill as a clear water scour countermeasure at a complex bridge pier. The investigation included three locations of the curved bed (at the upstream edge of the piles cap, 5cm, and 10cm toward the downstream), three elevations of the curved bed sill, and four elevations of the piles cap ranging from 0% to 75% of the pile cap thickness covered by bed materials. The results indicated that using a curved bed sill can reduce the scour depth in all cases with the relative piles cap elevations to its thickness up to 50%. Among those in this study, the most effective location was at the upstream edge of the pile cap, and its effectiveness increased directly with its elevation. This case recorded a scour depth reduction of up to 41%. Placement curved bed sill at the upstream edge of the piles cap can serve as an efficient scour countermeasure around the complex piers that will be constructed in the future and for existing piers, as it does not interfere with the pier foundation location.