Author(s): Jens Unger; Willi H. Hager
Linked Author(s): Willi H. Hager, Jens Unger
Keywords: Bridge hydraulics; Bridge scour; Failure; Riprap; Scour; Water flow
Abstract: Scour at bridge piers may be prevented by riprap placement. The latter is an addition to a pier to increase its performance against scour, therefore. This research presents (1) three basic scour mechanisms associated with circular-shaped bridge piers in rivers, (2) introduces a number of selected experiments and (3) describes a novel procedure for assessing the safety of bridge piers against failure. The procedure is based on an extended Shields approach accounting for the presence of a circular-shaped pier that is protected by a circular-arranged riprap layer of equal size elements. The design procedure degenerates to the entrainment condition of a pier for equal riprap and the sediment sizes, and to the Shields entrainment condition when the pier is removed.