Characterization of Bridge Foundations Workshop Report

EXECUTIVE SUMMARY

This report summarizes the findings from the "Characterization of Bridge Foundations" workshop held in Arlington, VA, from April 30 to May 1, 2013. The cross-discipline workshop included key staff members from the Federal Highway Administration (FHWA) hydraulics, geotechnical and structural disciplines brainstorming with stakeholders. The stakeholders included participants from five State transportation departments, academia, and industry.

The workshop initially discussed the issue of unknown foundations as it relates to hydraulic vulnerability for bridge scour. To determine the susceptibility of a bridge to scour, information on the foundation type and depth is needed. FHWA has provided guidance for risk-based analysis and field testing, and many of the States´ practices were discussed. The participants discussed the impact of multiple hazards on unknown foundations including other extreme events (seismic, post-event inspection, ship impact, etc.) as well as the issue of load testing of bridges with the unknown foundations.

The workshop led to an expansion of the scope of "unknown foundations" to include “foundation characterization” pertaining to condition evaluation of all bridge foundations whether known or unknown. The engineering problems associated with foundation characterization include assessing foundation type, pile type, embedment depth, geometry and material, foundation integrity, and load carrying capacity.

Discussions during the workshop also focused on the changes in service loads and foundation reuse issues from the perspective of the FHWA and State transportation department personnel. The main concerns with foundation reuse are the ability to assess their condition, their load carrying capacity, the remaining service life, and how the reuse of foundations interacts with new codes and standards. Further expanding the scope of the Research and Development (R&D) program to include foundation reuse was recognized as it also benefited the unknown foundations.

The Workshop provided a platform to discuss pertinent issues as it relates to foundation characterization with key players, both at the State and Federal level. This knowledge shared during the workshop, including existing gaps and recommendations, will be considered by FHWA as it develops its R&D program and a roadmap for the new Characterization of Bridge Foundations (CBF) program.