Generalized Reliability Model for Local Scour around Bridge Piers of Various Shapes

Authors: A. MELİH YANMAZ, İSMAİL ÜSTÜN

Abstract: Excessive local scour around piers and abutments is known as a major cause of bridge failure induced by hydraulic deficiencies. Complexity of the scouring phenomenon and high degrees of uncertainties in governing parameters lead to an unavoidable risk in bridge pier design. In this paper, a generalized reliability model based on static resistance-loading interference is developed for the assessment of reliability of bridge scour for various pier shapes. In the model, the relative maximum scour depth and the linear combination of the relative approach flow depth and flow Froude number are defined as the system resistance and external loading, respectively. By examining sets of data, a two-parameter bivariate lognormal distribution is found to represent the joint probability density function of the resistance and loading. Reliability expressions are developed for various pier shapes. To obtain relevant information for decision-making, the model is applied to a case study in which a relationship is obtained between the reliability and safety factors for cylindrical and non-cylindrical piers under various return periods.

Keywords: Reliability, Bridge pier, Scour, Pier shape, Resistance, Loading, Safety factor, Return period.

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