The 85th Street North Bridge is a seven span post-tensioned haunched slab bridge with a typical span of 26 meters for the middle five spans, and 20 meters at the ends. This 170 meter long bridge accommodates two lanes of traffic reaching over the Wichita Valley Center Floodway. VSL post-tensioning systems utilized for this project include 5-19 longitudinal tendons as well as 6-4 transverse tendons.

Post-tensioned haunched slab bridges are noted for ease of construction. Once the geometry of the bridge falsework has been obtained, prefabricated spacer frames are set into place. The spacer frames serve as templates for profiling the longitudinal post-tensioning tendons and aid in the placement of the remaining conventional reinforcement. Transverse tendons maintain mid-depth placement along the geometry of the haunched slab and provide the minimum pre-compression over the length of the structure.

The fi nished product has several advantages over conventionally reinforced concrete. Dead loads are balanced by the use of longitudinal post-tensioning reducing the sustained loading and associated creep. Corrosion resistance is increased due to the encapsulation of the post-tensioning reinforcement. Through the use of transverse post-tensioning, added compression improves the longevity of the structure by adding resistance to de-icing methods such as salt and magnesium chloride. Post-tensioned haunched slab bridges allow for a larger span to depth ratio than that of conventionally reinforced haunched slab bridges. The labor and material savings on mild reinforcement is another clear advantage to using post-tensioning for this application. Post-tensioned haunched slab bridges are not only a superior economic solution, but they are also aesthetically pleasing and a design trademark in the state of Kansas.