Dynamic Behavioral Analysis Of Concrete-Filled Steel Tubular Arch Bridges

In the past decades’ years, Concrete filled steel tubular (CFST) arch bridge as a newly-developing bridge type has been rapidly developed along with the development of transport in China. As the span of CFST arch bridge become larger and larger, conducting the analyses of arch bridges’ response when the structure is under the dynamic loads such as earthquake and wind takes on its important theoretical senses and practical values for Structural design.In this thesis, the author analyzed the characteristics of the CFST, reviewed the history of its development, presented the research on the state and development trend for CFST arch bridges, and introduced the contents and analytical methods of dynamic behavioral analysis of arch bridges. On the basis of design information of Song’ao Bridge, the author established 3-D finite element model of it with the universal FEM software SAP2000, discussed the difference of model and actual structure.Because CFST arch bridges’ response when the structure is under the dynamic loads is nearly correlative with natural vibration feature, seeking natural vibration feature is the precondition and base to carry through dynamic analysis. In this thesis, taking the example of Song’ao Bridge, the author calculated and analyzed its natural vibration feature, and analyzed the effects of natural vibration feature of the differences of structure parameters. Taking into account the difference of model and actual structure, and the difference of bridge structure, such as the arrangements of cross braces and the arrangements of suspenders, and the distinctness of material characteristics of bridge components, such as the rigidity of arch rib, the effects of these parameters on natural vibration feature was studied.In this thesis, taking the example of Song’ao Bridge, CFST arch bridge’ seismic response was studied by response spectrum analysis method and time-history analysis method. The standard seismic response spectrum was adopted to analyze structural seismic response which the seismic response spectrum was inputted from longitudinal, transverse and vertical direction respectively. Structural working state in. the most unfavourable seismic loads combination was preformed. Arch bridges’ response to uniform excitation of earthquake was analyzed by time-history analysis method. Structural seismic response that seismic wave was inputted from vertical direction were discussed. Structural seismic response that seismic wave was inputted from every direction were compared and discussed for checking computation the seismic safety of the structure. The effects of seismic behavior of the arrangements of cross braces were briefly discussed.