Enhanced camber and deflection estimation for AASHTO prestressed concrete girders

Abstract

The current camber prediction procedure in the PCI Design Handbook: Precast and Prestressed Concrete results in variations between the design and the actual camber. These variations create difficulties in maintaining the design thickness of the bridge deck and the design longitudinal profile. This research aims at enhancing the PCI design method of estimating long-term camber and deflection of prestressed concrete girders. Field measurements included monitoring cambers for a total of 94 girders from fabrication through the erection at bridge sites. Compressive strength and modulus of elasticity were measured for several girders, and the results were compared with the design properties. The differences between the design and actual concrete properties were found to be the main reason for overestimation in camber and deflection. A modification to the PCI camber prediction method is proposed to improve the accuracy of predicting the erection camber based on field measurements and material tests on four types of bridge girders.