Sunday, June 14, 2009

Osaka Bay Bridges: Minato Bridge

The Minato Bridge is a Gerber truss structure that spans between Sakishima Island and the Port of Osaka in Osaka Bay. The center span was brought to the site on a barge and lifted into place with winches attached to the cantilevered ends.
It is a double-deck bridge with side spans of 235 m and a center span of 510 m. The bridge is part of the Wangan Expressway and is just south of the Tempozan Bridge. It was built in 1974 for the Hanshin Expressway Public Corporation (HEPC) at a cost of 25 billion yen.

The seismic criteria for Japan has changed quite a bit since 1974 and so this bridge was retrofitted a couple years ago with isolation bearings between the decks and the floor beams and with buckling restrained devices for the towers. More information on the retrofit is at: www.idi.or.jp/tech/quarterly/idi37.pdf

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