扣件失效下轨道⁃箱梁结构振动特性试验研究

Experimental study on vibration characteristics of track-box girder structure with fastener failure

  • 摘要: 为研究扣件失效对桥上无砟轨道振动特性的影响,利用既有无砟轨道⁃箱梁结构缩尺模型,研究了随机荷载作用下不同扣件失效工况对轨道⁃箱梁结构振动响应的影响。研究结果表明:当扣件失效时,轨道⁃箱梁结构跨中截面各部件均出现了加速度导纳峰值增大以及导纳峰值频率前移的现象,且在钢轨和轨道板处变化尤为显著。失效扣件与观测截面的距离不同时,轨道⁃箱梁各部件振动响应也不同,当失效扣件在观测截面左右一个扣件间距范围内时,轨道⁃箱梁各部件加速度导纳显著增大,其中轨道板处导纳峰值增大1.48倍;当失效扣件距离观测截面超过3个扣件间距时,箱梁各板件加速度响应增幅均在5%以内。轨道⁃箱梁结构各部件动力响应增幅与扣件失效数量成正比,轨道板处连续失效3个扣件时加速度导纳峰值与无损伤时相比增大1.9倍;箱梁顶板及翼板处导纳峰值最大增幅分别为131%和82%,而箱梁腹板及底板处变化较小,峰值响应增幅约在25%以内。

     

    Abstract: To study the influence of the vibration characteristics of ballastless track on bridge under the failed fasteners, this thesis adopts an existing scale model of ballastless track-box girder structure. Under the random loading, the influence of different invalid fasteners conditions on the vibration response change of the track-box girder structure is discussed. The results show that the peak value of acceleration admittance increases and the peak frequency of admittance moves forward when the fastener fails, it appears in each component of the mid-span section of track-box girder structure, especially appears in the rail and track plate. At the same time, it is found that when the distance between the failure fastener and the observed section is different, the vibration response effect of the rail-box girder components is also different. When the distance between the failure fastener and the observed section within one fastener spacing, the acceleration admittance of each component of the track-box girder increases significantly, with the peak value at the track plate increasing by 1.48 times. When the distance between the failure fastener and the observed section is more than three fastener spacings, the acceleration response increase of each component of the box beam is within 5%. In addition, it is found that the dynamic response of various components of the track-box girder structure is directly proportional to the number of failed fasteners. For example, the peak acceleration admittance of the three fasteners with continuous failure at the track plate is 1.9 times higher than that without failure of fasteners. The maximum increase of peak admittance at the top plate and wing plate is 131% and 82% respectively, while the increase of peak admittance at the web plate and bottom plate of the box girder is approximately less than 25%.

     

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