A New Connection Detail Reduces Cost of Double Tee Bridges

The prestressed concrete double tee bridge may be the structure of choice for short- to medium-range spans where speed of construction is an issue. Primarily used on offsystem roads, this mode of construction is receiving more attention because of increasing labor costs associated with the pan form bridge that has been in use for well over 50 years in these circumstances. An important issue in double tee construction is the type of connection used to join the edges of adjacent tee flanges. When only an asphalt wearing surface is applied to the completed structure, these connections are the only means by which a tee supporting wheel loads is able to share loading with neighboring tees and hence gain the structural efficiency necessary to make this type of construction viable. Figure 1 shows the detail currently used by the Texas Department of Transportation (TxDOT). It is made from a combination of steel plates embedded in the edge of the tee flange during fabrication and a pair of steel angles that are field welded to these embedded plates to complete the connection. The assembly is typically spaced longitudinally at 5-ft intervals along the length of the bridge.