The great majority of the bridges in the United States have spans less that 100 ft (30 m). A large percentage of these bridges are either structurally deficient or functionally obsolete. This paper presents a new precast concrete composite bridge superstructure system called the Inverted Tee System (IT) consisting of inverted tee precast, prestressed concrete beams with a 6.0 in. (150 mm) cast-in-place topping. The IT beams are simple to produce in a single set of forms for various depths. The system is intended to provide an alternate to the cast-in-place slab bridge system that does not require field formwork and that can be installed with relatively small construction equipment. The proposed system has a span-to-depth ratio of up to 35, making it shallower than other available precast concrete products. The new system is shown to be structurally efficient, rapid to build, and economically competitive. The results of the analytical and experimental work used to develop the proposed system are presented. Several IT bridges are already in various design stages by the Nebraska Department of Roads and other agencies.
