Buffalo Creek Bridge: A case study of empirical versus traditional bridge deck design

Abstract

This paper presents a case study of the Buffalo Creek bridge structure under two conditions, one with an empirical sandwich deck referred to as “old deck design” and the other with traditional deck referred to as “new deck design”. The focus of the study is to assess the performance of the empirically designed reinforced concrete bridge decks versus those designed using traditional analytical design methods and to check the adequacy of both design methods by correlating the theoretical results with field observations. For this purpose, two 3D finite element models of the old deck and new deck designs were developed together with the bridge superstructure. Both models were subjected to real life loading configurations of self weight and temperature variations. A comparison of the stresses induced in both models indicates that the stresses developed in the empirically designed concrete deck (old design) at the levels of the reinforcing mats are similar to those developed in the traditionally designed deck. The connections between the steel main girders and the concrete deck are the main constrains for deck expansion and contraction in the transverse direction, hence high tensile stresses were developed over the girders in the transverse direction. Additionally, the sharp edge of the clip angle protruding into the concrete deck as well as the top of the slope of the stay-in-place forms were identified as stress risers that contribute to the longitudinal cracking problem.