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A key issue in the control, health monitoring, and condition assessment of civil structures is the estimation of structural modal parameters based on measured structural responses. However, field measurements of structural responses from civil structures under strong wind or earthquake excitations usually exhibit non-stationary feature and therefore cannot be adequately deal with by traditional modal identification methods. In this study, a novel procedure is integrated for modal parameter identification of civil structures from non-stationary structural responses on the basis of the variational mode decomposition (VMD) technique. First, the VMD algorithm is applied to decompose measured vibration signals into individual mode components. Then, the random decrement technique (RDT) is employed to obtain free vibration response of each mono component. Next, normalized Hilbert transform (NHT) is used to estimate modal natural frequency and damping ratio. The performance of the developed approach is evaluated using simulated non-stationary responses of a frame structure, and the identified results are validated. The effects of crucial factors such as levels of noise involved in structural response and data length on the modal parameter estimations are examined through detailed parametric study. Furthermore, the approach is applied to modal identification based on field measured non-stationary responses of a high-rise building during Typhoon Nida. The case study illustrates that the integrated method is an efficient tool for estimating the modal parameters of civil structures from non-stationary structural responses. [ABSTRACT FROM AUTHOR]

Highlights • A Kalman filter based inverse method for wind force identification is developed. • The method allows simultaneous estimation of wind loads and structural responses based on limited responses. • The feasibility of the method is evaluated based on wind tunnel test results and filed measurements. • The validations show the method can accurately predict wind loads on tall buildings. Abstract An inverse method based on the discrete time Kalman filter is developed to simultaneously estimate the unknown wind-induced responses and wind loads of high-rise buildings using limited response measurements. The accuracy and effectiveness of the presented estimation method are assessed based on both wind tunnel test results and field measurements of wind effects on a super-tall building. The wind-induced responses obtained by wind tunnel test are used to identify the wind loads on the super-tall building and evaluate the effects of crucial factors, such as covariance matrix of noise, initial estimation error, noise in measurements, modelling errors of structural dynamic properties and number of vibration modes, on the identification results. In addition, the wind loads are also estimated based on the field measured displacements during Typhoon Neoguri. Comparisons between the identified wind loads from the field measured displacements and the wind tunnel test results are made to verify the applicability of the inverse technique. The results of this study illustrate that the proposed inverse method is an efficient tool for predicting the wind loads on super-tall buildings from limited measurements of structural responses. [ABSTRACT FROM AUTHOR]