Elastomeric Bearings for Steel Trapezoidal Box Girder Bridges

Traditionally, bridge bearings supporting steel trapezoidal box girder (a.k.a. tub girder) superstructures consist of fabricator designed mechanical devices, such as pot or disk bearings (a.k.a. high load, multi-rotational bearings), that may be guided or unguided and are typically expensive to fabricate and place. The performance of these bearings has been mixed, with some being maintenance free and others requiring significant maintenance, repair and/or replacement. In Texas, bridge bearings supporting concrete and steel superstructure types are typically steel- laminated elastomeric bearings that are tapered or have a constant thickness. Recently the Texas Department of Transportatio n has moved toward the use of these structurally engineered elastomeric bearings for steel trapezoidal box girders in place of mechanically engineered pot or disk bearings. This paper presents a discussion of the rationale for the use of elastomeric bearings for steel trapezoidal box girders, a historical overview of bridge bearing systems in Texas, and the design procedure for the elastomeric bearings of the steel trapezoidal box girders of the US 290 & IH 35 Interchange built in Austin in the late 1990s and place in service in 2001.