Aerodynamic loads correction method based on wavelet packet transform in high-frequency force balance tests

Abstract

High-frequency force balance (HFFB) technique is a commonly used method for acquiring wind-induced response of tall buildings in wind tunnel tests. However, the resonance buffeting of the balance-model system (BMS) results in the distortion of measured aerodynamic loads. When the signal distortion is complicated due to additional vibration modes and noise interference, the existing methods fail to obtain correction results. Thus, a new correction method based on wavelet packet transform (WPT) is proposed in this paper to address the issue. The distorted signals are decomposed by WPT, and the relationship between wavelet packet coefficients and power spectral density (PSD) estimation is established. Then, the reference line that conforms to the aerodynamic attenuation characteristics is extracted by a single-degree-of-freedom (SDOF) correction method combined with a parameter identification method. Subsequently, the wavelet packet coefficients of SDOF correction results are adjusted according to the reference line. Finally, the time history of the aerodynamic load after correction is reconstructed by inverse WPT (IWPT). The proposed method is validated by a numerical example and applied to a HFFB test. Compared with the existing methods, the proposed method can address more complex distortion scenes and extend the correction frequency range to the Nyquist frequency.