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以地形模型风场测试为手段,测试了山区峡谷桥址的平均风水平分布特性。在风洞试验所得颤振导数的基础上,采用阶跃函数对桥梁断面自激力进行模拟,并对模拟准确性进行了分析与校核,继而推出时域颤振动力有限元分析过程中桥梁断面自激力的递推表达式。在此基础上,最后考虑峡谷桥梁桥面处平均风速的水平分布,对大跨度悬索桥颤振稳定性进行了数值分析。分析结果表明:考虑峡谷平均风速沿加劲梁展向不均匀分布后对桥梁颤振临界风速值有明显的影响,较大幅度地提高了临界风速值。相比之下,按目前我国公路桥梁抗风设计规范取水平向均匀分布风速进行山区峡谷桥梁进行颤振稳定性验算会得到偏于保守的结果。
With the wind field test of terrain model as a measure, the average wind and horizontal distribution of mountain canyon bridge site was tested. Based on the flutter derivative obtained from the wind tunnel test, the step function is used to simulate the self-excitation of the bridge section, and the simulation accuracy is analyzed and checked. Then the bridge in the finite element analysis of the time-domain flutter dynamic is introduced Recurrence expression of cross section self - excitation. On this basis, the horizontal distribution of average wind speed at the gorge bridge deck is finally considered, and the flutter stability of the long-span suspension bridge is numerically analyzed. The analysis results show that considering the average wind speed of canyon along uneven distribution of stiffening girder has obvious influence on critical flutter value of flutter of bridge and greatly increases critical wind speed value. In contrast, according to the current wind and highway design standards for highway bridges to take uniform horizontal distribution of wind speed for mountain canyon bridge flutter stability check will be more conservative results.