Stability of Highway Bridges Subject to Scour

Abstract

A common design/construction procedure for highway bridges in Alabama is the use of steel HP piles driven into a firm stratum with a length above ground/water up to the level of a concrete bent cap which supports the bridge superstructure. The use of 3, 4, 5, or 6 such piles in a row with the two end piles battered are very common bridge pile bents. The bents are sometimes encased in concrete from the bent cap down to three feet below ground level and sometimes the piles are X-braced in the plane of the piles for lateral support. The objectives of the Phase I research work were to identify the primary parameters of importance in assessing the adequacy of bridge pile bents for extreme scour events, and to identify the best approach to follow in developing a simple “screening tool”, to check the adequacy. The objective of the Phase II research work was to develop a simple “screening tool” and a user’s guide explaining the proper use of the tool, for use in evaluating the structural stability of simple pile bent-supported bridges in an extreme scour event. The objectives of this Phase III research work were to expand, refine, and automate the “screening tool” developed in Phase II work. This thesis presents the expansions, refinements, and Tier-2 screenings added to the original “screening tool”. The computer automation of the refined/2nd edition “screening tool” presented in this thesis is presented and discussed in a sister Phase III thesis.