Effect of pre-stress on natural vibration frequency of the continuous steel beam based on Hilbert-Huang transform

Abstract

To study the relationship between the natural vibration frequency of continuous steel beam and the pre-stress, based on two methods, namely experiments and numerical simulation, the continuous beam model under different pre-stress values was excited through using the hammering method, and the acquired vibration signal was divided and analyzed dependent on Fast Fourier Transformation (FFT) and Hilbert-Huang Transform (HHT), respectively. The applicability of the two analytical methods was compared, and meanwhile, the relationship between the vibration frequency of the beam and the stress was obtained. As known from the analytical result, the relationship between the vibration frequency of the beam and the pre-stress cannot be explained better based on the conventional mechanic’s theory, and instantaneous frequency of the beam cannot be captured through the currently used FFT method, thus difficult to obtain the relationship between them. Nevertheless, the relationship between the vibration frequency of the beam and the pre-stress can be obtained better through the instantaneous frequency of the beam and other indicators that was calculated dependent on HHT method. The natural vibration frequency of the beam was increased along with the rising pre-stress, and meanwhile, the vibration amplitude of the instantaneous frequency of the beam was also enlarged correspondingly. Finally, the numerical simulation model was also built to calculate the corresponding results and compared with those of HHT method. The relative small error was presenting in the experimental result and numerical simulation result, thus indicating the reliability and accuracy of the HHT method.