H型截面细长杆件颤振稳定性试验研究

Experimental study of flutter stability of H-shaped slender member

通过节段模型与气弹模型风洞试验,研究了不同腹板开孔率的H型细长结构的风致颤振失稳特性。试验中H型杆件的腹板与翼板宽的比值为2.4,试验研究均在均匀流中进行,来流风为横桥向时定义为0°风偏角。节段试验研究发现,腹板开孔的细长H型截面杆件在20°风偏角附近较低风速下即可发生扭转颤振失稳,发生扭转颤振失稳的风偏角区间受腹板开孔大小影响明显。腹板开孔率38%的模型在0°附近及10°<β<30°偏角区间存在扭转颤振失稳,开孔率27%的模型颤振失稳区间为10°<β<30°,而14%开孔率的模型颤振失稳区间仅为15°<β<25°。腹板无开孔的模型在0°≤β<10°偏角内较低风速下即可发生弯曲驰振,风偏角增大后,个别偏角下会发生扭弯颤振。腹板开孔为14%与27%的模型试验中没有观测到弯曲驰振现象,而开孔率为38%的模型在80°≤β≤90°偏角内可发生弯曲驰振,可见适度的腹板开孔可有效改善细长H型截面杆件的弯曲驰振稳定性。开孔率为27%的气弹模型试验验证了节段模型扭转颤振失稳及驰振稳定性的结果。

An experimental study of flutter instability of H-shaped slender member with different sizes of slotted web is carried out using both section models and aeroelastic model. The ratio of width to height for the testing models is 2.4, and the wind tunnel tests are performed in the uniform flow. Wind velocity transverse to bridge is defined to 0°. Testing results from the section models show that torsional flutter instability .initiates at a lower wind velocity for the models with web holes under the wind incidence of around 20°, and the wind incidence angles occurred flutter instability are great influenced with the size of web slot. The wind incidence angles which may induce flutter instability are around 0° and 10°-30° for the area ratio of 38% and that for the section models of area ratio of 27° and 14% reduce to 10°-30° and 15°-25°, respectively. Gal- loping is observed at angle from 0° to 10° for the model without web hole, and torsional flutter also occurred at some wind incidence angles. No galloping is observed under the wind incidence angles from 0°to 90° for the section models with area ratios of 14% and 27%, whereas galloping is observed at angles from 80° to 90° for the model with area ratio of 38%. It is seen that proper web slot has a significant positive effect to prevent the galloping instability. The test results of the aeroelastic model with area ratio of 27% further confirm the torsional flutter instability and galloping stability of the section models.