Reliability Analysis of Existing Bridge Deep Foundations for Reuse

There are great economic incentives motivating the reuse of existing bridge foundations when obsolete, deficient, or deteriorated superstructures are replaced or retrofitted. In many cases, these foundations still have significant functional values. Substantial time and cost savings can be realized when existing foundations are reused, and any capacity obtained from existing elements reduces the need to install costly new elements. While existing foundations have demonstrated load carrying capacity, many also have uncertain properties due to incomplete background information or lack of access for integrity and deterioration evaluation. In some cases, existing foundations may require strengthening, retrofit, or improvements for potentially higher or different loading conditions. This research proposes a simplified and practice-based approach to maximize the usefulness and available capacity of an existing foundation that can meet the target reliability prescribed by modern design codes. This is done by accounting for the static design equations, static load testing on individual piles, information on past loading history, and any load testing performed on the bridge.