Hydrological Aspects of Bridge Design: Case Study

Abstract

Many bridges are destroyed or fail completely during severe floods. If the cause of the damage is not a structural deficiency, it may be excessive local scour around bridge piers and/or abutments. Although the mechanics of the local scour around these obstacles has been studied extensively, the studies investigating the hydrologic design aspects are limited in the literature. Insufficient hydrologic and hydraulic evaluations may result in uncertainties in bridge design. The optimum return period for a flood hydrograph may be determined through a hydro-economic analysis for bridge design. Lack of relevant hydrologic data, such as precipitation and runoff may lead to difficulties in obtaining the design parameters. Realistic judgment of the hydrologist on the local hydrologic behavior of the project area is then required. In this paper, a case study performed for the hydrologic design of a bridge located in a small basin subject to frequent floods is presented. Scour computations of the bridge have been performed for various combinations of runoff to check the foundation stability.