Operational modal identification and finite element model updating of a coupled building following Bayesian approach

Abstract

Summary This paper presents a comprehensive study of the full-scale ambient vibration test, modal analysis, finite element (FE) modeling, and model updating of a coupled building in Hong Kong. The coupled building comprised a main part and a complementary part. To capture the dynamic properties of the building, a 21-setup ambient vibration test was designed and conducted. The modal parameters of each setup were identified following a fast Bayesian fast Fourier transform approach, and the partial mode shapes from the different setups were assembled following the least squares method. The identified modal parameters were analyzed and discussed in detail, revealing certain features of the coupling effects between the main and complementary parts. To determine the equivalent Young's moduli of various structural components, an FE model of the coupled building was developed and updated with the identified modal parameters. The Bayesian approach was followed to explicitly handle the uncertainties induced by modeling error and measurement noise. To ensure the model updating method is applicable even in unidentifiable cases, a Markov chain Monte Carlo simulation was employed in the proposed method to generate samples for approximating the posterior probability density functions of uncertain model parameters. The close match between the modal parameters calculated from the updated FE model and those identified from the measured time-domain data verified the validity of the proposed FE model. This study provides valuable experience and information for the development of structural model updating and structural health monitoring of building systems.