Direct observations of non-stationary bridge deck aeroelastic vibration in wind tunnel

Abstract

It is useful to study the ambient non-stationary response of a cable-supported bridge to monitor the "aeroelastic status" of the structure. In the absence of effective non-stationary analyzing tools, it is suitable to have signal processing techniques to pre-examine the measured ambient responses for the time scale at which the aeroelastic system varies to know if the recording can be treated as a quasi-stationary process or must be treated as non-stationary one. Among the factors contributing to the non-stationarity, the effect of signature turbulence is studied in this paper by joint time-frequency analysis on wind tunnel experiments with a partially streamlined box girder sectional model. Hilbert transform combined with empirical mode decomposition method is used. Instantaneous frequency domain properties of the aeroelastic vibration are obtained. Time-dependant features of the interactive system are partially revealed.