Reliability Analysis of Riprap Layer around a Bridge Pier Under Multiple Failure

The placement of riprap stone around the bridge pier generally used to protect the pier against scouring. To achieve the precise safety of riprap stone the design should be based on probabilistic sense by incorporating the all types of uncertainties involved in various effective parameters. A reliability analysis of riprap layer using the first order reliability analysis method (FORM) based on spreadsheets constrained-optimization technique has been carried out around a bridge pier for clear water condition in the present study. The reliability analysis for shear, winnowing and edge failure of riprap layer were also investigated separately and result in terms of reliability index and probability of failure were presented. To observe the effect of various parameters on the stability of riprap layer the sensitivity analysis has also been carried out for each failure mode.