大跨度非对称悬索桥的颤振稳定性研究

为了研究大跨度非对称悬索桥在不同非对称类型下的颤振稳定性,以主跨为628 m的某主缆不等高支承悬索桥为工程背景,基于全模态的三维频域颤振分析方法对悬索桥进行颤振稳定性分析。利用ANSYS建立了主缆不等高支承(支承高差0～40 m)和边跨跨度非对称(边跨跨度差0～40 m)悬索桥有限元分析模型,并编制相应双参数搜索迭代的APDL计算程序进行三维颤振稳定性分析。结果表明:在构造不等高支承悬索桥时,随着支承高差的增大,低阶模态频率变化较小,高阶模态范围逐渐减小; 弯扭频率比随着支承高差增加而不断减少,高差越大弯扭频率比降低越快; 桥梁颤振临界风速随着支承高差增大而不断降低,使得由于主缆不等高支承高差所引起的非对称结构形式对大跨度悬索桥梁结构的颤振稳定性有所降低; 在构造边跨跨度非对称悬索桥时,弯扭频率比随着边跨跨度差增加而减小; 随着支承跨度差的不断增大,悬索桥梁结构的颤振临界风速不断减小,但减小幅度很小,影响不大,在边跨跨度差较小时几乎可以不考虑对悬索结构的颤振稳定性影响。

Study on Flutter Stability of Long-span Asymmetric Suspension Bridges

In order to study the flutter stability of long-span asymmetric suspension bridge under different asymmetric types, a suspension bridge with unequal height support and main span of 628 m was taken as the engineering background. The flutter stability of the suspension bridge was analyzed based on the full modal three-dimensional frequency domain flutter analysis method. The finite element analysis model of suspension bridge with unequal height support(height difference was 0-40 m)of main cable and asymmetric side span(side span difference was 0-40 m)was established by ANSYS, and the corresponding two-parameter search iterative APDL calculation program was compiled for three-dimensional flutter stability analysis. The results show that when the unequal height suspension bridge is constructed, with the increase of the bearing height difference, the low-order modal frequency changes little and the high-order modal range decreases gradually. The bending-torsion frequency ratio decreases with the increase of the support height difference. The larger the height difference, the faster the bending-torsion frequency ratio decreases. The critical wind speed of bridge flutter decreases with the increase of support height difference, which makes the flutter stability of long-span suspension bridge structure decrease due to the asymmetric structure caused by the unequal height difference of main cable. When constructing side span asymmetric suspension bridge, the bending-torsion frequency ratio decreases with the increase of side span difference. With the increase of the difference of supporting span, the flutter critical wind speed of suspension bridge beam structure decreases, but the difference is very small, almost no effect. When the difference of side span is small, the flutter stability of suspension cable structure can be almost ignored.