Operational Modal Analysis for Vibration Control Following Moving Window Locality Preserving Projections for Linear Slow-Time-Varying Structures

Abstract

Modal parameters can reflect the dynamic characteristics of the structure and can be used to control vibration. To identify the operational modal parameters of linear slow-time-varying structures only from non-stationary vibration response signals, a method based on moving window locality preserving projections (MWLPP) algorithm is proposed. Based on the theory of “time freeze”, the method selects a fixed length window and takes the displacement response signal in each window as a stationary random sequence. The locality preserving projections algorithm is used to identify the transient modal frequency and modal shape of the structure at this window. The low-dimensional embedding of the displacement response data set calculated by locality preserving projections (LPP) corresponds to the modal coordinate response matrix, and the transformation matrix corresponds to the modal shape matrix. The simulation results of the mass slow-time-varying three degree of freedom (DOF) and the density slow-time-varying cantilever beam show that the new method can effectively identify the modal shape and modal natural frequency of the linear slow-time-varying only from the non-stationary vibration response signal, and the performance is better than the moving window principal component analysis (MWPCA).

Modal and Structural Identification of Historic Bell Tower in Čuntić, Croatia Using Ambient Vibration Testing

“…The bell tower was damaged during the Petrinja earthquake in such a way that its functionality was compromised, so an evaluation of its seismic resistance is required. Recently, the application of the results of experimental determination of modal parameters with AMT for different buildings has gained importance [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Gentile and Saisi [15] presented the results of investigations based on ambient vibrations carried out to evaluate the structural condition of a masonry bell tower built in the XVII century and about 74 m high.…”

An Adaptive Operational Modal Analysis Method Using Encoder LSTM with Random Decrement Technique

“…In addition, the modal parameters can be directly applied to the on-line health monitoring and damage diagnosis of the structure. What is more, for some complex and large structures, such as aerospace vehicles, offshore platforms, and bridges, it is difficult to measure the excitation under the actual working conditions, so it is of great engineering significance to identify the modal parameters directly from the timedomain response signals of the structure [1][2][3][4]. Conventional modal analysis methods usually assume that the excitation of the structure is white noise, but in fact, in the working state of the structure, the ambient excitation is mostly non-white noise.…”