Test Research On Vortex-induced Vibration Of Long Span Arch Bridge

With the application of new materials as well as development of design and construction technique, the span of modern bridges has constantly increased. Bridges orient progress towards long span, slender girder, small damp, flexible and light structure. Bridges are sensitive to the action of wind and their dynamic response are distinct. Aeroelastic problems often restrict the design of structure strength, rigidity and stability. Wind induced vibration (aeroelastic effect) of long span bridges has become the vital problem in the fields of bridge engineering and wind engineering. In the practical project, arch rib and girder of the arch bridge are always bluff sections, such as rectangle and trapezoid etc, which occur vortex-induced vibration easy on the action of wind. Vortex-induced vibration is limited amplitude response, but it occurs at low wind speed with relative large amplitude, which will affect the strength and fatigue resistance of the structure. Therefore, it is significant to research the vortex-induced vibration of long span arch bridge. At present, there are few research on dynamic response of long span bridges even published literature. While with the development of national economy, there are many constructing and having constructed long span arch bridges at west region, whose vortex-vibration effect at complicated wind environment should be researched. This paper basing on Chongqing Chaiyuanba bridge, researches it's vortex-induced vibration by wind tunnel test. In order to insure the credibility and trueness of the test result, full bridge aeroelastic model is made strictly according to similarity theory. At the same time, finite element calculation and spot checking are put into effect. The model completely meet the demand. The wind tunnel test carries out in the turbulent and uniform wind field, spire, fence and roughness element are used for simulating the wind environment of the bridge located site. Response of the arch rib and girder section for wind action is tested in finished dead state and four construction stage at different wind direction. The test results indicate that the arch rib occurs remarkable vortex-vibration at biggest cantilever and quarter arch rib state, while girder doesn't occur vortex-vibration at whole test process. Regularity of wind induced vibration varied with wind speed and wind direction are obtained by comparing and analyzing the test results.