Project of Kiso River Bridge and Ibi River Bridge. New Meishin Expressway; Kisogawahashi/Ibigawahashi no keikaku. Daini Meishin Kosoku Doro

The bridges on the new Meishin expressway which cross the Kiso River and the Ibi River in Mie Prefecture have the lengths larger than 1k and the span of about 160m each, and they must be designed as huge bridges. From the viewpoints of economical efficiency and workability, the first PC steel composite continuous extradosed bridge in the world is planned. The outline is given with emphasis laid on the superstructure work. PC box girders are employed near the side span and the intermediate support, and steel box girders are used near the central member of the center span for integration, and well balanced design becomes possible with the least total cost for the substructure and superstructure works because of the decrease in the dead weight and increase in the span length. In connection with the design policy, the structure and the PC cable are described. Precasting segment method is adopted for the PC box girder member. As to the design, reports are made on the location of joining PC box girder and steel box girder, sectional form of the main beam, diagonal cable, and the structure of the support. 8 figs., 1 tab.