Adjacent precast concrete box-beam bridges: State of the practice

This paper provides information about the current practice for the design, construction, maintenance, repair, and inspection of adjacent precast concrete box-beam bridges. These bridges provide a popular and economical solution in many states because they can be constructed rapidly and deck forming is eliminated. The bridges may be single or multiple spans. The box beams are generally connected by grout placed in a keyway between each unit and usually with transverse ties. Partial- or full-depth keyways are typically used, incorporating grouts using various mixture proportions. Transverse ties, grouted or ungrouted, vary from a limited number of nontensioned threaded rods to several high-strength tendons, posttensioned in multiple stages. In some cases, no topping is applied to the structure, while a noncomposite topping or a composite structural slab is added in other cases. Most shear-key details currently used are regional standard details of uncertain origin. This information was gathered from a survey of state highway agencies through the AASHTO Highway Subcommittee on Bridges and Structures and a review of the AASHTO LRFD Bridge Design Specifications.