Study On The Dynamic Characteristics And Seismic Performance Of Continuous Composite Box-girder Bridge With Corrugated Steel Webs

Composite box-girder bridge with corrugated steel webs which originated in the 1980 s gives full play to the material properties of concrete and steel,and has been developed and applied rapidly in France, Japan and other countries with its advantages such as light weight, high prestressing efficiency, economy and beauty as well as the significantly shortened construction period and so on. Over the past decade, more attention has been paid gradually to the composite box-girder bridge with corrugated steel webs in our country, and its research, application and development has just been unfolding.With modern bridge develops to the direction of lightweight, high strength, large-span and the frequent occurrence of earthquakes disasters, bridge structure as the lifeline engineering, the importance of its dynamic performance and seismic design has become increasingly prominent. At present, research on the composite box-girder bridge with corrugated steel webs made by domestic and foreign scholars mainly focused on the static performance, the study on its dynamic performance is relatively less. With the continuous expansion of the construction scale of such bridges, in-depth study on its dynamic problem is urgently needed.Based on consulting a large number of domestic and foreign research data, this paper discussed the development course, structural features as well as the technical advantages and disadvantages of the box-girder with corrugated steel webs, expounds the research status of dynamic characteristics and seismic responses of this kind of bridge. Taking a continuous composite box-girder bridge with corrugated steel webs which has been built in domestic as the prototype, a fine finite element calculation model of the bridge has been established by using the large-scale finite element analysis software, and the dynamic characteristics were analyzed. An equivalent girder model of composite box-girder bridge with concrete webs was built according to the principle of equal shear which the webs suffered, the comparison and analysis on dynamic characteristics of the two models were conducted. Selection methods of the ground motion parameter were discussed with reference to relevant regulatory requirement, seismic response spectrum analysis on the established girder model of continuous composite box-girder bridge with corrugated steel webs was conducted. Seismic history analysis was conducted to the spatiotemporal coupling dynamic model by selecting three appropriate Seismic waves, and the seismic performance of this kind of bridge was studied.The analysis results showed that, the use of corrugated steel webs instead of traditional concrete webs could effectively reduce the self-weight of the structure, improve the shear stiffness in section of the structure, but the longitudinal and lateral bending stiffness as well as the torsion rigidity in section were declined in different degrees at the same time. The first ten order vibration frequency of the girder were smaller than the corresponding vibration frequency of traditional concrete box-girder bridge girder with 10%~20%,and the torsional component appeared in the first ten order vibration mode, this is mainly because the rigidity of the box-girder bridge with corrugated steel web is smaller than stiffness of box-girder with concrete web. Therefore, the vertical seismic design of bridges should be strengthened in actual seismic applications.