双主跨悬索桥颤振节段模型试验模态匹配问题

Mode matching problem of sectional model flutter tests for a suspension bridge with double main spans

摘要:

多主跨悬索桥颤振节段模型风洞试验存在模态匹配问题,为了明确该类试验如何匹配竖弯模态与扭转模态以及哪种弯扭模态组合的颤振临界风速最低,以马鞍山大桥为工程背景,根据模态相似性匹配出3种弯扭模态组合,在节段模型风洞试验中测试了各组合的颤振临界风速,并对结果进行比较分析．结果表明:相同攻角下,一阶反对称竖弯与一阶反对称扭转模态组合的颤振临界风速最低,因此该组合是双主跨悬索桥二维颤振的控制组合;相同攻角下,一阶对称竖弯与一阶对称扭转模态组合的颤振临界风速略高于一阶反对称竖弯与一阶对称扭转模态组合的颤振临界风速;古典耦合颤振的Van der Put公式和Selberg公式能够预测各组合的颤振临界风速相对大小关系,但不能准确预测颤振临界风速数值．

Abstract:

Mode matching problem exists in sectional model flutter tests for a suspension bridge with double main spans. It is necessary to figure out how to match bending modes with torsional modes and seek the mode combination with minimal flutter critical wind speed. According to mode similarity of the Maanshan bridge, three mode combinations were selected. Flutter critical wind speed of every mode combination was tested in wind tunnel tests of sectional bridge model, and then these results of wind tunnel tests were analyzed. The research results show that the mode combination with minimal flutter critical wind speed is the combination matched by first-order antisymmetric vertical bending mode and first-order antisymmetric torsional mode, and it is the key mode combination for flutter of a suspension bridge with double main spans. The flutter critical wind speed for the mode combination of first-order symmetric vertical bending mode and first-order symmetric torsional mode is slightly greater than that for the mode combination of first-order antisymmetric vertical bending mode and first-order symmetric torsional mode. As for empirical formulas of classical coupled flutter, the Van der Put formula and the Selberg formula can estimate the relative value relationship of flutter critical wind speeds for different mode combination, but can’t estimate accurate values.