Identification of a Dynamic System Using Ambient Vibration Measurements

Abstract

This paper demonstrates how ambient vibration measurements at a limited number of locations can be effectively utilized to estimate parameters of a finite element model of a large-scale structural system involving a large number of elements. System identification using ambient vibration measurements presents a challenge requiring the use of special identification techniques, which can deal with very small magnitudes of ambient vibration contaminated by noise without the knowledge of input forces. In the present study, the modal parameters such as natural frequencies, damping ratios, and mode shapes of the structural system were estimated by means of appropriate system identification techniques including the random decrement method. Moreover, estimation of parameters such as the stiffness matrix of the finite element model from the system response measured by a limited number of sensors is another challenge. In this study, the system stiffness matrix was estimated by using the quadratic optimization involving the computed and measured modal strain energy of the system, with the aid of a sensitivity relationship between each element stiffness and the modal parameters established by the second-order inverse modal perturbation theory. The finite element models thus identified represent the actual structural system very well, as their calculated dynamic characteristics satisfactorily matched the observed ones from the ambient vibration test performed on a large-scale structural system subjected primarily to ambient wind excitations. It is noted that newly developed optical fiber accelerometers were used for this ambient vibration test. The dynamic models identified by this study will be used for design of an active mass damper system to be installed on this structure for suppressing its wind vibration.

Modeling and Prediction of Flexural Strength of Hybrid Mesh and Fiber Reinforced Cement-Based Composites Using Artificial Neural Network (Ann)

“…ANN has been helpful in solving structural engineering [30] and construction engineering related problems [21]. This includes structural analysis and design [31], [32], prediction of load-deflection of CFRF strengthened RC slabs [15]; prediction of shear capacity of concrete beam [27], [33]- [36], and shear strength of steel-fiber reinforced high strength concrete deep beams [24], prediction of moment capacity of ferrocement members [19], detection of structural damage [37]- [38], identification of structural system identification [39]- [40], modeling of material behavior, structural optimization [41] and structural dynamics and control [42].…”

Dynamic analysis of a cable-stayed deck steel arch bridge

“…The first identification method employ is Peak-Picking (PP), which has been used with success in many other applications [5,11,15,16]. This method is based on the fact that when the frequency response function reaches a peak at a certain frequency, it can be associated to the force or to a resonance frequency of the structure [17].…”

Modal parameter estimation based on the wavelet transform of output data

“…System identification using ambient vibration measurements presents a challenge, requiring the use of special identification techniques, which can deal with very small magnitudes of ambient vibration contaminated by noise. In such cases, a promising technique is the use of the random decrement technique, [3,4], which is a special averaging procedure to obtain, free responses.The aim of this paper is to show how the wavelet analysis of the free response of a system allows the estimation of modal parameters. The paper is organised as follows.…”