Removal, examination and testing on the Chousei bridge and the Taihei bridge which are the first prestressed concrete bridges in Japan

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The Chousei bridge and the Taihei bridge are the first prestressed concrete bridges (PC) in Japan, which were constructed in 1953 and 1954 across the Misogi river in Nanao city in Ishikawa Prefecture. After symbolizing the birth of PC bridge in Japan for 50 years, the bridge was earmarked for relocation as part of an urban development project. They were dismantled in August 2000 and in September 2001. Following its removal, some of the girders were subjected to examination and load testing to determine both the physical and chemical properties of old concrete and the load-bearing capacity of old bridge. The water to cement ratio of the concrete was found to be as low as 33 % and it texture was also very dense. This proves that the concrete mixed for bridge is very durable, which results in no carbonation of concrete and little corrosion of stee bars and PC wires in concrete. The bending and shearing load capacity of girders of the gbridge was also found to be satisfactory for the requirements of specifications of road bridges. After the test, the Chousei bridge was relocated to the memorial park on the outskirts of Nanao city.