【摘要】 为研究大跨人行悬索桥非线性静风失稳的内在原因,以主跨420m天蒙人行悬索桥为背景进行分析。综合考虑几何非线性与静风荷载非线性,采用内、外双重迭代算法从定性与定量的角度分析该桥非线性静风失稳发展过程及失稳临界形态。结果表明:大跨人行悬索桥静风失稳发展路径为,不断非线性增大的加劲梁位移牵连主缆和抗风缆产生相对于加劲梁的竖向位移,使主缆和抗风缆逐渐消减拉应力,直至抗风缆接近松弛而失稳;静风失稳临界形态是以加劲梁扭转变形为主、竖弯变形为辅的复杂弯-扭耦合空间变形状态;静风失稳内在原因为,静风升力和升力矩随附加风攻角的增长不断增大,加劲梁和缆索系统的静风位移持续增大并产生相对竖向位移,导致缆索系统刚度大幅卸载。更多还原

【Abstract】 To study the inherent causes of the nonlinear aerostatic instability of long span pedestrian suspension bridge,the Tianmeng Pedestrian Suspension Bridge having a main span of 420 m was taken as an analysis object and comprehensively considering the geometric nonlinearity and the aerostatic load nonlinearity,the inner and outer double iteration algorithm was used to qualitatively and quantitatively analyze the development process of the nonlinear aerostatic instability and the critical state of the aerostatic instability of the bridge.The results of the analysis reveal that the development path of the aerostatic instability of the long span pedestrian suspension bridge is that the nonlinearly increasing displacement of the stiffening girder of the bridge causes the main cables and wind cables to have the vertical displacement that is relative to the girder,makes the tensile stresses of the cables gradually reduce and until the wind cables approach to the relaxation,causes the aerostatic instability to occur.The critical state of the aerostatic instability is the spatial deformation state of the complex bending and torsion coupling characterized mainly by the torsion deformation and secondarily by the vertical bending deformation of the girder.The inherent causes of the aerostatic instability are the aerostatic lift and the incessant increase of the lift moment changing with the increase of the additional wind attack angles.The incessant increase of the aerostatic displacement of the girder and the cable systems and the produced relative vertical displacement all results in the great unloading rigidity of the cable systems.更多还原