Simulation and Advanced Second Moment Reliability Analyses of Pile Groups Using CPGA-R: Formulation, User's Guide, and Example Problems

More than 50 of the US Army Corps of Engineers locks and their approach walls have continued past their economic lifetimes. As these structures wear out, they must be retrofitted, replaced, or upgraded with a lock extension. Innovative designs must be considered for Corps hydraulic structures, particularly flexible approach walls, and new tools for evaluating these designs must be developed. The Computer- Aided Structural Engineering CASE computer program CPGA performs basic pile group analyses using Saul s method. It is intended to be a simple program to aid in the rapid pile group analysisdesign of the Corps hydraulic structures that are founded on groups of piles. The analysis uses the stiffness method, with the pile cap assumed to be rigid and the piles assumed to be linearly elastic. Soil resistance to pile movement may be included. Probabilistic data generated during a reliability analysis of Corps hydraulic structures is formally used in risk and reliability engineering for major rehabilitation studies. Reliability studies deal with the demand on a system and the capacity of the system to respond to that demand. Both the demand and capacity can contain uncertainty, so the interaction of demand and capacity also will be uncertain. A reliability index can be determined for the uncertain interaction, and the probability of unsatisfactory performance can be determined from the reliability index. This report deals with the extension of CPGA to include the generation of probabilistic data and application of risk-based methods to the analysis of the Corps pile group-founded hydraulic structures. The software is named CPGA-R, with the R referring to the new reliability analysis capability. CPGA-R uses both Advanced Second Moment ASM and Importance Sampling Simulation reliability analyses techniques.