The Influence of Overhang Construction on Girder Design

Overhangs on bridges result from economical constraints to use as few girders as possible across the bridge width. While designers commonly employ rules of thumb to define overhang geometry, the rules generally lead to unbalanced loading that is not considered in the design. The overhang brackets are connected to the top of the fascia girder and react against the side of these girders. Due to the eccentricity of the overhang, a torsional load is applied to the fascia girder. The torsional load causes the girders to twist and can affect both the global and local stability of the girders. The deformational behavior of the girders is generally not well understood and is sensitive to the construction details. Depending on the geometry, the overhangs can lead stability problems in both steel and concrete girder systems. To improve the understanding of overhang behavior, three Texas bridges were monitored during the concrete deck construction to collect data for validation of a 3-D finite element model. The results the field monitoring are presented in this thesis.