阶跃函数模拟桥梁断面气动自激力的精度研究  

Precision investigation on the self-excited aerodynamic force model of bridge decks simulated by indicial functions

作　　者：吴长青 张志田 WU Chang-qing;ZHANG Zhi-tian(College of Civil Engineering and Architecture,Hunan Institute of Science and Technology,Yueyang 414006,China;School of Civil Engineering and Architecture,Hainan University,Haikou 570228,China)

机构地区：[1]湖南理工学院土木建筑工程学院,湖南岳阳414006 [2]海南大学土木建筑工程学院,海南海口570228

出　　处：《振动工程学报》2024年第6期997-1005,共9页Journal of Vibration Engineering

基　　金：国家自然科学基金重点资助项目(51938012);海南省自然科学基金创新团队项目(520CXTD433);湖南省教育厅优秀青年项目(23B0645)。

摘　　要：介绍了采用阶跃函数模拟桥梁断面时域气动自激力的方法并对模拟的精度进行了研究。提出了采用现代遗传优化算法进行阶跃函数参数识别的方法。在模拟桥梁断面时域自激力的过程中,建立了颤振导数与阶跃函数各参数之间的等量关系,基于MATLAB平台实现了遗传优化算法并识别了阶跃函数的各个参数,根据参数值与上述等量关系反算得到颤振导数的拟合值,并通过对比颤振导数的拟合值与试验值来评估模拟的精度。数值算例表明,遗传优化算法的计算效率很高且不受参数个数与参数取值范围的影响;阶跃函数参数个数对颤振导数拟合精度存在较大的影响;当参数个数较少时,对于较为复杂的颤振导数曲线,拟合精度不高。随着参数个数的增加,拟合精度显著提高。拟合精度直接影响后续时域颤振分析得到的桥梁颤振性能;因此,需要依据颤振导数曲线规律,合理地选取阶跃函数的参数个数,才能建立精度较高的时域自激力模型,进而准确评估桥梁的颤振稳定性能。This paper introduces a method of using indicial functions(IFs)to simulate the time-domain expressions of self-excited aerodynamic loads of bridge decks,and studies the precision of this simulation.A modern genetic optimization algorithm is pro-posed to identify the parameters of IFs based on the tested flutter derivatives.During the simulation process,the equivalent relation between flutter derivatives and IFs parameters is first established.Then,the genetic optimization algorithm is implemented to iden-tify all the IFs parameters using the MATLAB software.Based on the obtained IFs parameters,the fitted flutter derivatives are calculated according to the relation expression between IFs parameters and flutter derivatives.Finally,the simulation precision is evaluated by comparing the fitted and tested flutter derivatives.Numerical results indicate that the genetic optimization algorithm has high computational efficiency and is not affected by the number or range of parameters.The number of IFs parameters greatly influences the fitting precision of the flutter derivative.When the number of IFs parameters is small,the fitting precision is not ideal for complex flutter derivative curves.As the number of IFs parameters increases,the fitting precision significantly improves.The difference in fitting precision directly affects the critical wind speed of flutter obtained by the subsequent time-domain flutter analy-sis.Therefore,it is necessary to carefully select the number of IFs parameters based on the properties of flutter derivative curves.This allows for the simulation of a high-precision time-domain self-excited aerodynamic loads model,which can accurately evaluate the flutter stability of long-span bridges.

关 键 词：桥梁 颤振 时域 阶跃函数 遗传优化 

分 类 号：U441.3[建筑科学—桥梁与隧道工程] TU312.3[交通运输工程—道路与铁道工程]