Exterior girder rotation of skew and non-skew bridges during construction

Abstract

In bridge design, bridge decks regularly overhang past the exterior girders in arrange to extend the width of the deck whereas constraining the specified number of girders. The overhanging part of the deck comes about in uneven eccentric loads to the exterior girders which are by and large most prominent. These eccentric loads are primarily a result of bridge construction operations as well as the weight of new concrete and other construction live loads. These unbalanced loads can lead to a differential edge deflection of overhang deck and a rotation of the exterior girders. The girder rotation or differential deck deflection can also affect local and global stability of the entire bridge. The objective of this study is to enhance the knowledge and understanding of external girder behavior due to unbalanced eccentric construction loads and to identify the critical factors affecting their rotation. In this article, field data obtained during the construction of two skewed (one with a small skew (3.8°) and the second with a severe skew (24°)) and one non-skewed steel girder bridges are described, and a detailed comparison is presented. The three bridges experienced maximum outward exterior girder rotation during construction which subsequently decreased following construction operations. The field results were used to validate and calibrate the finite element models. The numerical and field-monitored data showed good agreement and can be used to assist bridge designers and construction engineers to design appropriate systems to limit girder rotation during construction.