扭心偏移对桁梁桥颤振临界风速影响的试验研究

Tests for effects of torsional center offset on flutter critical wind velocity of a truss bridge

近些年山区大跨度桁梁桥得到较多的修建,其颤振性能通常由弹性节段模型风洞试验确定。试验中,主梁扭转中心通常设在节段模型的形心。受多种因素的影响,大跨度缆索桥梁主梁扭心可能偏离了形心位置,从而导致风洞测试结果与实际情况出现偏差。通过节段模型风洞试验模拟桁梁桥的扭心竖向偏移,测试不同扭心偏移下大跨度斜拉桥与悬索桥的颤振临界风速,对比研究扭心偏移形成的弹性转动中心、质量惯性矩、扭转频率变化的影响。总体上,扭心偏离形心使得桁梁桥颤振临界风速提高。

A great number of long-span truss bridges are built in mountainous areas nowadays. Their flutter performance is usually determined through their elastic sectional model wind tunnel tests. In tests,their main girder torsional centers are set at centroids of the models in general. However,influenced by several factors,the main girder torsional center of long-span cable bridges may offset from its centroids to result in the deviation between the wind tunnel test results and the actual situation. Here,the vertical offset of the torsional center of a truss bridge was simulated through its sectional model wind tunnel tests. Flutter critical wind velocities of a long-span cable-stayed bridge and a long-span suspension one with different torsional center offsets were measured. The effects of elastic rotating center formed due to torsional center offset,moment of inertia,and torsional frequency on these bridges’ flutter critical wind velocities were contrastively studied. The results showed that as a whole,the torsional center offset from centroid causes increase in a truss bridge’s flutter critical wind velocity.