| Summary: | 碩士 === 淡江大學 === 土木工程學系 === 90 === This thesis investigates the effects of deck’s width-to- depth ratio (B/D) on bridge buffeting by wind tunnel section model test. Scheme of data interpretation was carefully constructed to properly relate measurements of scale-down section model of a long span bridge to the prototype. Two basic deck shapes were selected for wind tunnel test in this study. One is a better-streamlined box section; the other is a plate girder section. Four B/D ratios were used for each model. The result indicates that, for a properly constructed and properly interpreted bridge’s section model test, the onset flutter velocity and buffeting response of its prototype can be estimated within a reasonable margin of error. This research project further shows that smaller the B/D ratio accompanied with a smaller vertical buffeting response. As for the torsional buffeting, B/D ratio does not cast distinct effect on the bridge response. In addition, reducing the B/D ratio of bridge deck tends to make bridge less aerodynamically stable, i.e., lower the onset flutter wind speed. Bridges with small B/D ratio also exhibit distinct vortex shedding resonance at relatively low wind speed.
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