Probablistic Bridge Pier Scour Factors

Abstract

Over the past 40 years, numerous studies have been conducted and equations developed to predict bridge-pier scour. Although it is desired to have a conservative approach to scour to increase our sense of safety and reliability, field experience often leads bridge and hydraulics engineers to suspect that the equations over-predict scour at a significant level. To date, few studies have been undertaken to quantify the reliability of the scour equations in terms of probability of exceedance. In this study, the authors used available laboratory data to determine the probability that the design scour will be exceeded using two pier scour equations, both recommended by the Federal Highway Administration: (1) HEC-18 equation and (2) FDOT equation.