不确定气动干扰效应影响下并列大跨度桥梁颤振导数识别方法

Identification Method of Flutter Derivative of Long-span Bridge in Tandem with Uncertain Aerodynamic Interference Effect

将处于自然风中一前一后并列布置的大跨度桥梁相互之间可能存在的不确定相互气动干扰处理成随机气动干扰,并归入到紊流风随机激励中,采用基于模态参数识别的随机子空间识别方法,开发了桥梁断面颤振导数识别的专用程序,并以具有理论解的Theodorsen平板为例,通过系统响应数值仿真和颤振导数识别,验证了该方法的可靠性。针对实际大跨度桥梁,设计了并列节段模型试验悬挂系统,开展了紊流风和随机气动干扰效应下的并列大跨度桥梁节段模型风洞试验,将迎风、背风侧桥梁断面的颤振导数结果与均匀流、紊流风中单个桥梁断面颤振导数值进行了对比。结果表明:背风侧桥梁对迎风侧桥梁的颤振导数影响很小,而迎风侧桥梁对背风侧桥梁的颤振导数有较大影响;该研究方法为存在这种随机气动干扰的并列大跨度桥梁颤振导数识别提供了一个较为合理的途径。

Uncertain interactive aerodynamic interference of two long-span bridges in tandem which located very closely in turbulent wind was treated as stochastic aerodynamic interference, and was included into stochastic turbulent wind excitation. Based on the stochastic subspace identification （SSI） method of modal parameter identification, specified program of flulter derivative of bridge section was developed. Taking Theodorsen thin plate with theoretical solution as example, the method was validated through system response simulation and identification of flutter derivative. Aimed at practical long-span bridge, suspension system of sectional model test in tandem was designed. Wind tunnel test of sectional model of long-span bridge in tandem under turbulent wind and stochastic aerodynamic interference effect was carried out. Flutter derivative results of windward and leeward bridge section got by the test were compared with flutter derivative value of single bridge section in smooth flow and turbulent wind. The results show that the windward bridge has notable influence on flutter derivatives of the leeward bridge, while the leeward bridge has little influence on those of windward bridge. The research method can provide a reasonable way for identification of flutter derivative of long-span bridge in tandem with stochastic aerodynamic interference.