桥下净高对大跨桥梁主梁气动特性的影响

发布时间：2018-01-28 14:10

本文关键词： 方柱矩形断面桥下净高主梁气动特性 CFD SSTk-ω模型　出处：《湖南大学》2014年硕士论文　论文类型：学位论文

【摘要】：大跨度桥梁由于结构形式和地形条件不同可能具有不同的桥下净高。跨河桥梁在雨季和枯水季面临显著的水面涨落，，跨海大桥受到气候和洋流等的影响，海面高度也会发生改变，这些因素都能够使得桥梁下部净高产生明显变化。大跨度桥梁结构柔度大，对风的作用敏感，因此这种由于桥下净高变化而产生的对桥梁主梁气动特性的影响在设计时不得不进行考虑。目前对这一问题的研究成果不多，因此本文对此进行研究，具体是通过计算流体动力学(CFD)方法，进行二维数值模拟分析。首先，对方柱绕流进行了二维数值模拟，以验证本文计算方法的合理性。得到了方柱三分力系数、涡脱斯托罗哈数St、方柱表面风压系数分布和流场特性等结果。计算结果与风洞试验吻合较好，表明本文采用的SSTk湍流模型具有良好的精度。对方柱绕流的雷诺数效应进行数值模拟，结果表明在1.0×103到1.0×105量级内，雷诺数效应不明显。然后，研究边界条件对矩形截面主梁气动特性的影响。选取宽高比为5的矩形截面主梁为研究对象，对不同桥下净高时，矩形截面主梁的绕流进行二维数值模拟。计算得到了矩形截面主梁三分力系数、涡脱斯托罗哈数St、矩形表面风压系数分布和流场特性等结果。对比各工况结果，定量分析了桥下净高对矩形截面主梁气动特性的具体影响。最后，研究桥下净高对大跨桥梁主梁气动特性的影响。选取某实桥闭口流线型钢箱梁断面为研究对象，对不同桥下净高下，桥梁主梁气动特性进行了二维数值模拟。计算得到不同桥下净高时，桥梁主梁断面三分力系数、涡脱斯托罗哈数St、桥梁主梁断面表面风压系数分布和流场特性等结果。对比不同桥下净高下的结果，定量分析了桥下净高对大跨桥梁主梁气动特性的具体影响。
[Abstract]:Long span bridges may have different net height under the bridge because of the different structural form and terrain conditions. The bridge beams are faced with significant fluctuations in the rainy season and dry season, and the bridge across the sea is affected by climate and ocean currents. The sea surface height will also change, these factors can make the bridge lower net height change obviously. Large span bridge structure flexibility, sensitive to the role of the wind. Therefore, the influence on the aerodynamic characteristics of the bridge girder caused by the change of the net height under the bridge has to be considered in the design. Two-dimensional numerical simulation is carried out by computational fluid dynamics (CFD) method. Firstly, two-dimensional numerical simulation is carried out to verify the reasonableness of the proposed method. The three-point force coefficient of the square column and the vortex de-Storoha number St are obtained. The results of wind pressure coefficient distribution and flow field characteristics on the square column surface are in good agreement with the wind tunnel test. It is shown that the SSTk turbulence model adopted in this paper has a good accuracy. The Reynolds number effect over a cylinder is numerically simulated, and the results show that it is in the order of 1.0 脳 10 ~ 3 to 1.0 脳 10 ~ 5. The Reynolds number effect is not obvious. Then, the influence of boundary conditions on the aerodynamic characteristics of rectangular cross-section main beam is studied. The rectangular cross-section main beam with ratio of width to height of 5 is selected as the research object, and the net height under different bridges is also studied. Two-dimensional numerical simulation of the flow around the main beam with rectangular section is carried out. The three-point force coefficient of the main beam with rectangular section and the vortex de-StoRoha number St are calculated. The results of wind pressure coefficient distribution and flow field characteristics on the rectangular surface are compared and the effects of net height under the bridge on the aerodynamic characteristics of the main beam with rectangular section are quantitatively analyzed. Finally, the effect of net height under the bridge on the aerodynamic characteristics of the main girder of the long-span bridge is studied. The section of a steel box girder with closed mouth is selected as the research object, and the net height under the bridge is reduced. The aerodynamic characteristics of the main girder of the bridge are numerically simulated in two dimensions. When the net height under the bridge is different, the cross-section force coefficient of the main girder and the vortex de-StoRoha number St are calculated. The results of wind pressure coefficient distribution and flow field characteristics on the surface of the main girder of the bridge are compared with the results of the net height under different bridges, and the specific effects of the net height under the bridge on the aerodynamic characteristics of the main girder of the long-span bridge are quantitatively analyzed.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3

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