中文摘要：

以大跨径钢管混凝土系杆拱桥为研究对象，利用有限元软件Midas Civil 建立空间有限元模型，分别对该桥在考虑桩-土作用下和刚性地基假定下的动力特性进行了深入的研究，得到结论：在考虑桩-土作用时，该桥出现的振型特点主要为拱肋面外振动、拱肋面内以及拱肋的空间扭转振动3 种振动形式，且随着振型阶数的增高，振动就越频繁，振型就越显复杂，还伴有耦合振型产生；该桥拱肋的横向刚度要远远小于其竖向刚度以及抗扭刚度；最后将考虑桩-土作用和按刚性地基假定计算下结构的自振特性进行对比可知，是否考虑桩-土作用对结构竖向刚度的影响较大，但是结构的横向刚度与竖向刚度之间的差距有所减小．

英文摘要：

With a long-span concrete-filled steel tube arch bridge as the research object,this study establishes a space finite element model using the finite element software Midas Civil,and conducts an in-depth research on the dynamic characteristics of the bridge under the effect of the piles and soil and the assumed rigid foundation,and then obtains the main vibration characteristics of the bridge in three vibration modes considering the pile soil interaction:out-of-the plane vibration of the arch rib,in-the-plane vibration of the arch rib and spatial torsional vibration of the arch rib;and with the increased number of modes of vibration,the more frequent of the vibration,the more complex the vibration type is,accompanied by the coupling mode;the lateral stiffness of the arch rib is far less than the vertical stiffness and torsional stiffness;finally,the research compares the calculation results of the natural vibration characteristics considering the pile and soil interaction and under the assumed rigid foundation structure,and finds that whether or not to consider the effect of pile-soil interaction has a great influence on the vertical stiffness of the structure,but the gap between the structure of the lateral stiffness and the vertical stiffness decreases.