White Steel for Osaka Bay

Robison, Rita; Kitazawa, Masahiko; ,

White Steel for Osaka Bay

by Rita Robison, Senior Editor; Civil Engineering, New York, NY,
Masahiko Kitazawa, (M.ASCE), Subchief; Higashi Kobe Construction Office, Kobe Construction Division, Hanshin Expressway Public Corp., Kobe, Japan,

Serial Information: Civil Engineering—ASCE, 1991, Vol. 61, Issue 2, Pg. 44-47

Document Type: Feature article

Abstract:

Wind, earthquake and aesthetics were the design determinations for Japan's Higashi-Kobe Bridge. The designers also had to consider the man-made bay infill site and a directive to build a spectacular gateway to the city of Kobe, spanning a 500 m wide channel. The main girder of the three-span, 885 m long bridge appears light and graceful. The Warren truss has no vertical members, and its steel upper and lower decks are integral with the main chords. The tower prongs are connected by low-placed crossbeams, from which the main girder is suspended rather than being fixed on the piers. This gives the bridge an unprecedentedly long natural period of longitudinal sway; about 4.4 s, reducing earthquake forces and, hence, size requirements for the towers and foundation. Vane-type dampers are installed on the end piers to control longitudinal oscillation. The steel decks are orthotropic slabs. To keep the channel open to shipping during construction, the towers are being constructed separately on the east and west banks, the main girder cantilevered from them, balanced by the backspans. The entire superstructure and 96 harp-patterned cables are to be painted white.

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