Investigation of Empirical Deck Design in Bridge Widening

Abstract

This paper presents the results from an investigation into the performance of concrete bridge decks designed with the empirical design method. Compressive membrane/arching action (CMAA) behavior in bridge decks has been known for many years and has been adopted in design codes by some countries. AASHTO LRFD Bridge Design Specifications have provisions that allow the use of the empirical deck design method, which is based on CMAA. Despite the savings in deck reinforcement that the empirical method offers compared with the traditional method, the majority of state departments of transportation (DOTs) do not allow the use of the empirical method. In part, this is due to the fact that some of the current method limitations (e.g., lack of sufficient overhang length) are impossible to satisfy in phased construction and future widening scenarios. In this study, the performance of concrete bridge decks designed with the empirical design method was investigated through extensive experimental testing of a full-size specimen. The fabricated deck specimen mimicked a widening scenario, where the deck was supported on two prestressed concrete Florida I-Beams. Nine tests were conducted at different locations along the bridge deck under service and failure load levels. The results show that deck slabs designed according to the empirical design method are capable of meeting AASHTO LRFD serviceability and strength requirements. The outcome of this research study provides information to DOT officials regarding the feasibility of using the empirical method for the design of bridge decks under conditions not currently covered by AASHTO LRFD provisions.