基于相似模型试验的简支箱梁振动传递特性研究

Study on Vibration Transmission Characteristics of Simply-supported Box-girders Based on Similarity Model Test

在模型相似理论研究的基础上,推导原型箱梁与模型箱梁在弹性阶段的相似关系,并以32m简支箱梁桥为原型,设计制作1/10缩尺箱梁模型,并利用有限元计算和模态试验的方法,验证1/10缩尺箱梁模型设计制作的正确性。最后,通过模型试验的方法,研究箱梁振动在各板件之间和纵向上的传递特性,并探讨不同支座刚度对箱梁振动特性的影响。结果表明:振动在板间传递过程中,顶板传递至翼板时的衰减速度最慢,随后是腹板,而振动由顶板传递至底板中衰减最快;在45~200Hz的频段内,顶板振动在跨中至1/4截面的距离范围内衰减快,在1/4至支座截面的距离范围内衰减慢,且部分箱梁模态频率会使箱梁局部振动得到加强;在20~200Hz范围内,支座刚度变化对部分频率的箱梁振动有一定影响,但影响程度有限。

Based on the model similarity theory,this article deduced the similarity relationship between the prototype box girder and the model box girder during the elastic stage. A 1/10 box girder scale model was designed and built with a 32 m simply-supported box girder bridge as the prototype. The similarity between the 1/10 model and the prototype was verified through modal experiment,together with finite element calculation. The vibration transmission characteristics between the plates and along the longitudinal direction were studied by means of model testing. The effect of different bridge support stiffness on the box girder vibration was discussed. The results show that the vibration undergoes the least mitigation when it transmits from the top plate to the flange,followed by the web and base plate. Within the frequency range of 45~200 Hz,the top plate vibration mitigates faster between the bridge mid-span to 1/4-span whereas it is slower between the bridge 1/4-span and the bridge support section. The modal frequencies of some box girders may enhance the local box girder vibration. Within the medium-high frequency range of 20~200 Hz,the change of the bridge support stiffness will result in a little impact on the structural vibration of the box girder mid-span. However,this impact is negligible.