| With development of express way construction in recent years gradually from plain-hill district to mountain-venturi district,more longger the span of bridges grow,more higher the bridge towers rise and more flexible the bridge system develops, Moreover,with new materials and new techniques in bridge engineering has been successfully applied continuously,As a new pier structure,the concrete-filled steel tube main pier across the valley have been applied to large-span rigid-frame bridge. So this long-span bridges on the seismic study put forward a number of new issues.So, taking the Labajin Bridge on the Yingjing section of Yalu Speedway as the engineering background, two methods including response spectrum and time-history analysis of earthquake are applied to a continuous rigid-framed bridge with a super high concrete-filled steel tube piers. The main content in this thesis includes:(1) Establishing four calculation models of the bridge;considering the influence of in the two-bridge of horizontal linkages and the pile-soil interaction;calculating the natural vibration frequency and analyzing the dynamic characteristics of the three models respectively.(2) The seismic response of the three models were analyzed by response spectrum and dynamic time-history analysis methods.By changing the speed of the earthquake wave,the traveling-wave effect were analyzed.(3) It is concluded that how affect the changes of the pier material and the pier cross-section in a continuous rigid-frame bridge seismic response with different seismic waves.The main conclusions from above include:(1) Setting the lateral linkages increases the lateral stiffness, weakens the structure of the lateral vibration, increases the axial force of the piers, decreases moment of the Pier bottom; The pile-soil interaction reduces the natural frequency and increases the moment of the span apparently;Vertical seismic force increases the structure of the axial force and girder moment.(2) Compared with the results of seismic response obtained by response spectrum,the results obtained by ime-history analysis method increases,We should adopt the larger result when design.(3) The influence of the travelling-wave effect on the high-span continuous rigid frame bridge can not be ignored. It is shown that travelling-wave effect causes different degree variations of bending moment at span, the top or the bottom of pier.(4) Changes in cross-section compared with pier pier materials is more obvious on the seismic response. Moreover, the choice of Seismic waves have a great impact in seismic response of bridge.It is expected to give some references for seismic design,construction and post-conservation of similar bridges. |
