Probabilistic design of riprap bed sills

Abstract

Flexible bed sills are extensively used in rivers for different purposes, one of them being the protection of buried assets such as pipelines. This paper proposes developments to enable the use of a probabilistic approach in the design of bed sills, covering arguably the most common material: riprap. A probabilistic design of bed sills is expected to lead to safer and more cost-effective designs. A methodology involving a number of stages for estimating the annual probability of bed sill failure is presented along with fragility curves that describe the probability of failure of the structure dependent on the loading or design conditions of the sill. The methodology is applied to a particular example to illustrate the advantages of the approach.