Design of the Shintomei-Nakatsukawa Bridge - An extradosed bridge considering effect of large displacement due to a fault

The Nakatsugawa Bridge is constructed over a valley with both ends linked to a tunnel. It was confirmed that there is a fault in the valley. This fault is likely to cause a relatively large vertical displacement, and fault fracture zones are distributed over a wide area. Considering these topographical and geological conditions, we planned a triple-span PC extradosed bridge which will prevent collapse in the event of a fault displacement, averting irreparable damages. Consequently, the side span is extremely short in comparison with the central span, because of space restrictions affecting arrangement of pylons and piers. This presented a challenge in that a significant imbalance between the spans might lead to a negative reaction at the girder end. This paper discusses a series of reviews made for bridge planning and design, and reports that the balance between the spans was improved successfully by using light weight butterfly webs exclusively for the central span.