Non-Gaussian Turbulence Induced Buffeting Responses of Long-Span Bridges

Abstract

Conventionally, for turbulence-induced buffeting vibrations, the Gaussianity assumption is applied to all three subsequent stages of turbulence, wind loads, and structural vibrations because of its wide applicability and mathematical simplicity. However, non-Gaussian turbulence does exist in the boundary-layer atmosphere, especially near the tropical cyclone center. Non-Gaussian turbulence represents short duration and high-speed airflow, which is unfavorable for structural dynamic performance and reliability. It is necessary to analyze the non-Gaussian turbulence effect on flexible structures, especially long-span bridges, and compare the wind-induced vibration against responses caused by conventional Gaussian turbulence. The time domain bridge buffeting analysis method with unsteady aeroelastic force and aerodynamic admittance approximated by rational function was employed to calculate the vibrations excited by Gaussian and non-Gaussian turbulence, which were simulated using the spectrum representation method and the Hermit polynomial translation process method. A Monte Carlo simulation of bridge buffeting was conducted in this study. The statistical results show that the bridge response, excited either by Gaussian or non-Gaussian turbulence, still follows the Gaussian process assumption. However, for the same wind speed, Monte Carlo simulation shows that the vibration amplitudes increases with turbulence skewness in terms of RMS and extreme values. However, the increment ratio decreases with greater mean wind speeds. The peak factors also increase slightly for greater turbulence skewness.