菜园坝长江大桥主拱节段风洞试验及分析

Investigation of section model of Caiyuanba Yangzi River bridge's arches in wind tunnel

中承式拱桥属于柔性空间结构,主拱上承受的脉动风荷载相互干扰。以重庆菜园坝长江大桥为研究对象,进行了湍流下的主拱单拱及双拱节段模型风洞试验。对模型表面脉动压力的功率谱、相关系数、水平和竖向相干函数进行了细致分析,讨论了双拱间距宽度比对脉动压力频域特性的影响。当间距宽度比大于5时,后拱风荷载受到前拱的干扰作用。当两拱间距宽度比小于5时,前后拱风荷载特性类似于组合截面。随间距宽度比变小,主拱涡脱落折算频率和压力功率谱逐渐增大,前后拱迎风面和背风面的相关系数及相干系数均逐步降低。

Long span arch bridge is a flexible space structure. Wind loads on double arches are disturbed each other. As an example of Chongqing Caiyuanba Yangzi River bridge, the wind tunnel tests of single arch and double arches section were carried out. The power spectrum densities, correlation coefficients and coher- ence functions in horizontal and vertical directions are analyzed in detail. The effects of space-width ratio of double arches on the fluctuating pressure are discussed in frequency domain. When space-width ratio of double arches is larger than 5, the loads of leeward arch are disturbed by the windward arch. While space-width ratio of double arches is less than 5, the wind loads on double arches are similar to the eomposited section arch. With space-width ratio decreasing the vortex frequency and power spectrum densities increase, while correlation coefficients and coherence functions about windward area and leeward area of double arches decrease.