Response of a Composite-Adjacent Box Beam Bridge with Skewed Beams under Static and Quasi-Static Loads

Abstract

Adjacent box beams are widely used for constructing short- and medium-span bridges on roadways throughout the United States. The performance of a straight, noncomposite-adjacent box beam bridge under a live load is well understood, while the behavior of a composite-adjacent box beam bridge constructed using beams poured into a form with a skew angle, known as a skewed adjacent box beam bridge, is not. The focus of this research is the evaluation of the in situ performance of the skewed composite-adjacent box beam bridge located on Dry Creek Road in Granville, Licking County, Ohio, which is a single-span bridge with a 28° skew angle. To evaluate the overall bridge behavior under live loads, the beams were instrumented with strain gauges and linear variable differential transformers (LVDTs). The live load testing was performed using a tandem axle dump truck and single-axle truck under both static and quasi-static controlled load conditions. The experimental results from the current work were used to evaluate three characteristics representative of bridge response: lateral load distribution, skew effect, and shear key relative displacement. This work proposes that the composite-adjacent box beam superstructure components behave as an integral unit resisting the applied load. Additionally, the skewed geometry distributes the strain asymmetrically across the width of the bridge. Most of the applied loads correspond to a diagonal path to the supports at the obtuse corners. The measurement of the relative displacement showed that most of the shear keys experience cracks. Ten months after the truck load test, the reflected cracks were visible on the bridge deck. The cracks occurred where the highest relative displacements were measured. The measured longitudinal tensile strain showed that the load is transferred effectively from one beam to another. The current work also suggests that the cracks developed in the shear keys do not have a significant effect on the load distribution between adjacent box beams because the presence of the composite deck enhances load distribution.