Restraint Moments in Precast/Prestressed Concrete Continuous Bridges

Abstract

To eliminate deck joints and shoulder piers, continuous span (jointless) bridges are becoming an attractive option. Different continuity methods and construction sequences have different time-dependent effects on the behavior of the bridge system. These effects are illustrated in this paper. To achieve a favorable performance of bridges made continuous for deck loads, recommendations for achieving continuity and for desirable construction sequence are presented. A new continuity detail using high strength threaded rods is proposed. Based on a cost comparison with currently available continuity methods and a full-scale NU1100 I-beam experiment, this continuity detail is shown to eliminate the potential for bottom concrete creep restraint cracking at pier locations and to increase the span capacity by as much as 20 percent.