Prestressed Beam End Reinforcement and Camber

摘要

This project deals with the behavior of precast pretensioned concrete bridge beams between the time of prestress release and the time of beam installation over the piers and abutments. In particular, there are two primary issues, reinforcement of beam ends for the bursting effects of the prestressing force at the time of release, and camber growth between release and installation. The first issue relates to the amount of reinforcement required to control end zone cracking to acceptable limits without creating excessive reinforcement congestion in the end zone. The second issue, camber prediction, is used for two purposes. First, when predicted and measured camber at the time of prestress release well, this indicates a quality control measure that the beam has been subjected to proper level of prestressing. Second, accurate predication of camber growth due to concrete creep between erection and installation will result in accurate control of final roadway profile and accurate predication of the quantity of cast-in-place concrete required to fill haunch between the girder top flange and the deck slab soffit.