Development of a Novel Type of Open-Web Continuous Reinforced-Concrete Rigid-Frame Bridge

Abstract

Long-span continuous reinforced-concrete rigid-frame bridges are sensitive to the shrinkage and creep of concrete and the relaxation of prestressing tendons and have experienced problems related to serviceability loss because of excessive multidecade deflections. Moreover, the large negative bending moment and shear force in the box girder near the piers may lead to cracks in the top slabs and webs. To improve the structural performance and mitigate the long-term deflection of bridges, a novel type of open-web continuous reinforced-concrete rigid-frame bridge was developed during the design of the Beipan River Bridge with a 290-m main span. In this paper, the design and construction techniques of the novel bridge type are summarized first. Then, a structural analysis of the Beipan River Bridge is conducted. The results are compared with conventional rigid-frame bridges. Moreover, the long-term girder deflections are checked through the combined application of monitoring data and finite-element analysis. The results show that the bridge alignment is quite stable during the first 5 years in service and that the open-web design philosophy can effectively mitigate the long-term girder deflections.