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Since the completion of the national project to build
long-span bridges between Honshu and Shikoku, the
construction of medium-scale bridges has become dominant.
The medium-scale bridges that require cost-effective
technologies will become the main stream of bridge
construction. The current design study on wind resistance
has also been handling medium-scale bridges.
This paper reports the development of cost-effective
two edge girders for a cable-stayed bridge, and of the
wind resistance design for the four-lane box girder of a
suspension bridge.
1) The aerodynamic characteristics of a two-edge girder
were examined using a wind tunnel, and the relation
between flutter onset velocities and the girder designs
was identified. From the analysis, a basic design consideration
was proposed for wind resistance.
2) The effects of grating, windshield screen and other
accessories to divert airflow were examined for a fourlane
box girder. The optimum design for wind resistance
has been derived for a combination of airflow
control accessories.
3) The shape effect of central opening was studied for
controlling aerodynamic pressure from the viewpoint
of wind resistance. Since its effectiveness for oscillation
control has been recognized, it will be further pursued to
establish a new type of wind resistance technology. |
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