摘要
为对结构动力响应进行有效分解并获得分解后振动响应的时频特征,提出了结构振动响应分解的扩展离散解析模式分解。基于扩展的离散解析模式分解,提出了截止频率选取的优化方法。传统的截止频率选取方法往往是根据傅里叶频谱图来进行人为选取。然而,对于具有密集模态成分的结构振动响应或者信噪比低的结构环境振动响应,很难根据傅里叶频谱图来选取截止频率。为了更好地对截止频率进行自动化优化选取,提出用自回归功率谱代替传统的傅里叶谱选取截止频率的方法。为验证扩展离散解析模式分解方法的有效性,首先对一模拟的结构振动信号进行有效分解;然后,对一个具有密集模态的36层框架结构的数值模拟,利用所提自回归功率谱法,获得了具有密集模态的振动信号的截止频率,并对结构振动信号进行了有效的分解;最后,以吉安赣江公路大桥为工程实例,选取了大桥环境振动加速度实验数据,利用自回归功率谱找出了信号分解中的截止频率;进而利用扩展离散解析模式分解获得了大桥的前两阶振动响应,并识别出了大桥的前两阶振型。结果表明:扩展离散解析模式分解是解析模式分解在离散信号处的有效延展;同时,利用自回归功率谱在扩展离散解析模式分解中寻找截止频率的方法更为有效。
To effectively decompose structural dynamic responses and obtain the time-frequency features of the decomposed components,this paper proposes an extended discrete analytical mode decomposition and a cut-off frequency selection method for structural dynamic responses analysis.In previous studies related to the analytical mode decomposition,the cut-off frequency is arbitrary selected from the Fourier spectrum.However,it is quite a challenge to select the cut-off frequency for a structural response with closely spaced components or with low Signal Noise Ratio ambient noise.In this paper,an optimization method for cut-off frequency selection based on the extended discrete analytic mode decomposition is proposed.The theoretical framework of the extended discrete analytical mode decomposition is first described.To automatically select the optimized cut-off frequency,a method based on the auto-regressive power spectrum is proposed to obtain the cut-off frequency.Then,the proposed method is verified by agenerated signal.A 36-story shear type building structure with close-spaced modes is simulated as a numerical example,and the cut-off frequency is effectively selected by using the proposed method.The response is finally effectively decomposed by the extended discrete analytical mode decomposition method.Finally,the measured dynamic accelerations of Ganjiang Highway Bridge is analyzed.The dynamic accelerations are effectively decomposed by the proposed method and the first two modes are extracted.The results show that the extended discrete analytical mode decomposition method combined with the auto-regressive power spectrum can effectively select the cut-off frequency and decompose the structural dynamic response,even when the response components are closely spaced.
作者
后军军
王佐才
任伟新
HOU Jun-jun;WANG Zuo-cai;REN Wei-xin(School of Civil and Hydraulic Engineering,Hefei University of Technology,Hefei 230009,China;New Theory and Technology Research Platform of Bridge Structure Safety Monitoring,Hefei University of Technology,Hefei 230009,China)
出处
《振动工程学报》
EI
CSCD
北大核心
2018年第3期365-373,共9页
Journal of Vibration Engineering
基金
国家自然科学基金面上项目(51578206
51478159)
安徽省杰出青年科学基金资助项目(1708085J06)
中央高校基本科研业务费专项资金资助项目(PA2017GDQT0022)
关键词
结构动力响应
解析模式分解
扩展离散解析模式分解
截止频率
自回归功率谱
structural dynamic response
analytical mode decomposition
extended discrete analytical mode decomposition
cut-off frequency
auto-regressive power spectrum
