SEISMIC ANALYSIS OF A LONG-SPAN CONTINUOUS STEEL TRUSS-ARCH BRIDGE COSIDERING TRAVELING WAVE EFFECT

摘要

The Nanjing Dashengguan Yangtze River Bridge is a 108+192+336+336+192+108 m six-span continuous truss-arch bridge on the Beijing-Shanghai High-speed Railway. As the character of the long span structure, the response of the main bridge considering the traveling earthquake wave effect should be calculated. An FEM model is established. The natural frequencies and mode shapes are acquired by the eigen-parameter analysis. By inputting the El Centro earthquake accelerations to the bridge system in association of Ex+0.3Ey+0.3Ez and 0.3Ex+Ey+0.3Ez components according to the Europe Code, the dynamic responses of the bridge, including the displacement and accelerations of the main nodes of the structure, and the seismic forces of the key members, are calculated by the structural analysis program, based on which the main laws of the seismic responses of the bridge are summarized, and the safety of the structure is evaluated. The displacement and internal force response of the main bridge excited by the El Centro earthquake with the traveling speeds of 300 m/s, 500 m/s, 1000 m/s and 2000 m/s respectively are compared with the final results obtained by the spectrum analysis and the common time history analysis.