大跨度斜拉桥气弹模型对结构静风响应的反应能力的数值研究

通过有限元方法探讨了全桥气动弹性模型主梁轴向刚度失真和主梁初内力失真的问题，以及它们对大跨度斜拉桥风致静力响应的反应能力。分析发现，两个失真因素均会较明显地导致实际结构的风致静力响应被低估，但两者对试验结果准确性的影响趋势可能相反而相互抵消。当两个失真因素同时作用时，风洞试验会低估实际结构主梁竖向风致静力位移10%左右，主梁侧向和扭转风致静力位移3%左右。由于斜拉桥风致静力失稳现象主要表现为主梁扭转发散，基于全桥气动弹性模型的风洞试验对大跨度斜拉桥风致静力响应的模拟结果在可接受的精度范围之内。

NUMERICAL STUDY OF THE RESPONSIBILITY OF STRUCTURAL AEROSTATIC RESPONSES IN AERO-ELASTIC MODEL TESTS OF LONG-SPAN CABLE-STAYED BRIDGES

Inaccuracies of the axial stiffness and internal force distribution of the bridge girder in aero-elastic full bridge models were studied by using the finite element method, and their influences on aerostatic responses of long-span cable-stayed bridges were examined. It is found that the inaccuracy of the axial stiffness and the inaccuracy of the internal force distribution can lead to significant underestimation of the aerostatic responses of the structure, but their effects can be counteractive and therefore offset the deviation from each other. When the two inaccuracies are involved simultaneously, the wind tunnel tests will underestimate the aerostatic responses of the bridge girder of about 10% in the vertical direction and 3% in the lateral and torsional directions. Since the aerostatic instability of cable-stayed bridges mainly presents as torsional divergence of the bridge girder, wind tunnel tests based on aero-elastic full bridge models are of acceptable accuracy for the aerostatic responses of long-span cable-stayed bridges.