Component and system-level reliability analysis of riprap layer around bridge pier in clear water condition

Abstract

ABSTRACT Placing riprap is considered as a permanent layer and common countermeasure against local scour around the bridge pier. However, the typical design of the riprap layer by using empirical equations fails to consider the uncertainties, which are involved in effective parameters on its characteristics such as the size, thickness, and extent. Therefore, there is no information about the probability of failure for the designed riprap layer. Accordingly, this study presented a method for the reliability assessment of the riprap layer considering the uncertainties which are involved in effective parameters. All three different characteristics of the riprap layer were included in the analysis by using the Monte Carlo Simulation Technique. In addition, Fault Tree Analysis was employed for combining the interactions of different parameters and calculating the probability of the failure of a riprap layer system. Further, a case study was provided to demonstrate the capability of the present method, followed by evaluating the effect of each effective parameter on the probability of failure using sensitivity analysis. The results revealed that relative riprap stone density and flow depth have the highest and the least effect on the probability of failure of riprap layer, respectively.