Based on an in-situ hammer excitation test,the vibration transmission characteristics of a 32-m-long simply-supported prestressed concrete box-girder in high-speed railway are investigated.A track-bridge coupled system model is established based on the finite element method to calculate the mobility of track slab,sub-base slab,and box-girder top slab in the frequency range of 1Hz to 1000Hz.The model is validated by comparing with the test results.The vibration transmission characteristics of the box-girder are studied and the influences of top slab thickness,middle web addition,stiffness and damping of used fastener system are discussed.Additionally,the vibration transmission characteristics of the box-girder under practical wheel-rail impact force are analyzed.Results show that the top slab mobility is the largest in the one-third octave center frequency range of 20Hz to 200Hz,and the flange slab mobility takes second place.While,the web slab and bottom slab mobilities are relatively small.The top slab vibration decays rapidly within a distance of L/8 (L denotes the box-girder span) from the exciting point,but decays slowly beyond that range.Increasing top slab thickness,adding a middle web,and increasing fastener damping are beneficial to the vibration and noise reductions.The vibration velocity of box-girder slabs under practical wheel-rail impact force is relatively high in the one-third octave center frequency range of 40Hz to 80Hz,in which induces significant structure-borne noise.%以高速铁路32m预应力混凝土简支箱梁为研究对象,基于现场锤击试验,探讨了铁路混凝土简支箱梁振动传递特性.采用有限元法建立了轨道-桥梁垂向耦合系统模型,计算了轨道板、底座板和桥梁顶板在1～1000Hz之间的垂向速度导纳,与试验结果进行了对比,验证了模型的可靠性.利用有限元模型研究了箱梁振动传递特性,讨论了箱梁顶板厚度、增设中腹板和扣件系统刚度、阻尼等参数对箱梁振动特性的影响,分析了行车激励下箱梁振动传递特性.研究结果表明:在1/3倍频程中心频率20～ 200Hz之间,顶板速度导纳最大,翼板次之,腹板和底板的速度导纳相对较小;顶板振动在距激励点L/8(L为桥梁跨度)范围内的衰减较快,在距离激励点L/8以外的衰减缓慢;增大箱梁顶板厚度、增加箱梁中腹板以及增大扣件阻尼等措施能在一定程度上减小桥梁的振动和噪声;在轮轨力激励下,箱梁各板件均在中心频率40～80Hz之间振动速度较大,由此可导致该频率范围内的结构噪声较大.
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