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该文详细介绍了有理函数与阶跃函数在桥梁气动自激力时域模拟中的应用。分别对两种表达式的极限特性与瞬态特性进行了分析。理论分析与数值结果表明:阶跃函数的极限特性独立于识别参数而与桥梁断面的准定常风荷载特性相一致,经参数识别后的阶跃函数自激力表达式是准定常风荷载模型与基于颤振导数表达的自激力模型两者的统一。因此,阶跃函数自激力模型可应用到响应均值非零的结构风振响应分析中。相比之下,有理函数模型的极限特性依赖于所识别的参数,与准定常风荷载特性并不存在统一的关系,因而通常情况下其应用范围限定在均值为零的桥梁风振响应分析中,该文通过分析讨论指出,可通过强制有理函数表达式中若干参数值的方法克服这一缺陷。无论是阶跃函数还是有理函数模型,由于其参数识别是按照自激力平稳谱特性等效的原则完成,因而其识别参数所决定的瞬态特性仅仅是一种数值结果,并不代表实际桥梁断面的瞬态气动力特性。由此可能会产生高瞬态值与十分耗时的衰减过程,这种不良瞬态特性会引起结构风振时域分析中长时间范围的自激力模拟失真。该文通过限定时域自激力表达式中记忆项参数的识别数值范围,有效地解决了这一问题。
This paper introduces the application of rational function and step function in time domain simulation of bridge aerodynamic self-excitation. The limit characteristics and transient characteristics of the two expressions are respectively analyzed. The theoretical analysis and numerical results show that the limit characteristic of the step function is consistent with the quasi-steady wind load characteristics of the bridge section independently of the identification parameters. The self-excited expression of the step function after the parameter identification is the quasi-steady wind load model and Unification of Self - excitation Model Based on Flutter Derivative. Therefore, the step function self-excited model can be applied to wind-induced response analysis of structures with non-zero mean response. In contrast, the limit function of the rational function model depends on the identified parameters and does not have a uniform relationship with the quasi-steady wind load characteristics. Therefore, the application scope of the rational function model is usually limited to the bridge wind-induced response analysis with zero mean This paper points out through analysis and discussion that this defect can be overcome by forcing some parameter values in the rational function expression. Both the step function and the rational function model, because its parameter recognition is based on the principle of self-excitation smooth spectral characteristics, the transient characteristics determined by the identification parameters are only a numerical result and do not represent the actual bridge Transient aerodynamic characteristics of cross section. As a result, high transient values and very time-consuming attenuation processes may occur, which can cause long-run self-excitation distortion in wind-induced vibration analysis of structures. This paper solves this problem effectively by defining the range of recognition parameters of the memory term parameters in the self-excited expression in time domain.