Research Of Seismic Isolation-Measures Of Long-Span Combined Road With Railway Cable-stayed Bridge

In recent years, the bridge construction has a great development in our country, especially the long-span cable-stayed bridge which has a remarkable development.The independent design and successful construction of Tian Xing Zhou Bridge and Su-Tong Bridge imply that the technology of long-span cable-stayed bridge construction and design in our country has reached international advanced level.In general, the long-span cable-stayed bridges play a great role in the national transportation and economic development; it’s not only have a bad influence on the rescue work after earthquake but also result in the serious economic losses and have a significant effect on the national transport network if the large span cable-stayed bridges are destructed in the earthquake. So taking the effective and sensible measures to protect the large span cable-stayed bridge against the earthquake and ensure the security of it has a considerable significance. However, there is no detailed seismic design of large span cable-stayed bridge in the existing highway or railway seismic design standard to date, because of this we should make the specialized analysis of seismic design. On the other hand, if we merely get the purpose of "against", what we got may at the expense of high cost. From this point, we put up with the idea of seismic mitigation and isolation, so we achieve the seismic purposes by the measures of seismic mitigation and isolation.In this paper, the author analyses a double tower and double cable of the combined road with railway cable-stayed bridge and on the basis of the history of the cable-stayed bridge development and the technology of bridge seismic and mitigation and isolation, with the help of professional finite element software MIDAS/CIVIL, finishing the following research:1、Establishing the research bridge’s dynamic finite element model and comparative analysing the dynamic characteristics of the research bridge by taking into account the pile foundation elastic and not considering the pile foundation elastic, which provides a reference for the follow-up work of this article.2、Based on the structural characteristics of the researched bridge, respectively setting longitudinal Earthquake-reduction cable and vertical viscous damper in the tower and beam as a shock absorber; through time history analysis,discussing the affect on the dynamic characteristics of the structure and the seismic response in the structure by setting the shock absorber; comparative analyzing the earthquake-reduction effects of longitudinal earthquake-reduction cable and vertical viscous damper and analysis in this paper shows that the main parameters of damper.3、Referencing a cross-Gulf cable-stayed bridge base isolation technology, setting isolation layer in the bottom of bridge tower and study analysis on the influence for the bridge earthquake response of the bridge to isolation layer.The article based the background of a bridge takes respectively different seismic mitigation and isolation measures and gets their influence on the earthquake response of bridge structure. The conclusion in this paper can be as a basis of seismic design of the researched bridge and as a reference for other similar bridge’s seismic analysis and earthquake-reduction design.