关键词: 桥梁工程, 悬索桥, 非对称, 静风稳定性, 失稳临界状态, 失稳过程

Abstract: In order to study the internal mechanism of the static wind instability of the long-span asymmetric suspension bridge, taking a suspension bridge with a main span of 628 m as the background, the corresponding ANSYS finite element model was established to analyze the static wind stability. Considering the nonlinear influence of the structure system and the static load, the instability process and critical state of bridge under static wind load were analyzed by double iteration method. The results show that the instability process of the long-span asymmetric suspension bridge is that the static wind displacement of the main beam increases nonlinearly, which leads to the increase of the relative vertical displacement of the main cable and suspender, and the stress of the main cable and suspender decreases continuously until the main cable and the suspender are close to the relaxation state and lose stability. The static wind instability mode is a complex three-dimensional instability state, in which the main girder is symmetric transverse bending and symmetric torsion, and the vertical displacement also has a great influence on it.The internal mechanism of static wind instability is that the increase of additional wind attack angle leads to the nonlinear increase of lifting moment and lifting force, the torsion deformation of main beam and the vertical displacement of cable, which leads to the decrease of cable stress and even local relaxation, and finally leads to the significant reduction of gravity stiffness of the bridge structure.

Key words: bridge engineering, suspension bridge, asymmetric, static wind stability, instability critical state, instability process