Bridge Scour Risk Assessment and Countermeasure Design

Abstract

Statistical surveys conducted on investigation of reasons of bridge failures implied that the majority of bridges have failed because of excessive scouring at infrastructural elements. A bridge crossing an alluvial river should therefore be designed properly with special reference to possibility of this action at piers and abutments. On construction of a bridge, its scour criticality should be examined regularly throughout the service life spans to take necessary actions promptly. The Federal Highway Administration (FHwA) developed a methodology and software named HYRISK to evaluate annual risk of scour failure of an existing bridge in monetary values. A case study is carried out for a bridge crossing Fol Creek in the Black Sea region of Turkey using this methodology, which is integrated with additional assessment methods for checking conditions of bridge elements and channel in close vicinity. The scour criticality of the bridge corresponding to existing and possible future conditions is obtained, and a feasible scour countermeasure is designed using HYRISK and an economic analysis.