Long-Term Performance of a Curved Box Girder Viaduct

Deformations due to environmental and mechanical loads in curved bridges can lead to fairly complex long-term effects. Instead of the one-dimensional longitudinal movement that occur in straight bridges, in curved bridges two-dimensional movements, i.e., longitudinal and transverse, need to be considered in the design stage and throughout the structure’s life span. Both deformations are related to the curvature and construction materials used in the bridge. Currently, both guided and nonguided bearings commonly are deployed to accommodate the movement and stresses caused by thermal movements in curved bridges. Bearings usually are oriented along the chord from the fixed piers of the bridge in current design practice. However, this traditional orientation is not compatible with bridge movements at each pier, which can induce excessive stresses in both superstructure and substructure. This study monitored and investigated a steel twin-box girder bridge. The fracture-critical bridge analyzed in this study lies on four horizontal and three vertical curves. Guided and nonguided expansion pot bearings are utilized, except on the fixed pier. Extreme temperature changes caused transverse superstructure movements and damage to the bearing guiding system. The monitoring system outfitted on the bridge recorded the temperature distributions as well as the bridge movement. The structural movement behavior due to temperature variation was studied, and the investigation of existing damage showed that both transverse and longitudinal movement were excessive and that the resultant forces transferred from superstructure to substructure were significant. The results indicate that a refined analysis always is required to account for curved bridges’ deformations in order to prevent structural damage.