Research On Turbulent Wind Characteristics And Its Effects On Buffeting Responses Of Bridge Girder Sections

In order to research characteristics of turbulent wind, aerodynamic admittance of bridge girder sections, and effects of various wind spectra on buffeting response of two-dimensional sections, the following work has been carried out with the help of wind tunnel tests and buffeting numerical calculation of sectional models:1. Long period on-site observation and corresponding statistic analysis of natural wind at Houjia town weather station of Chongming Island in Shanghai were performed. The characteristics of turbulent wind, including turbulence intensity, gust factor, integral length scale and wind spectrum, were summarized based on a large amount of measured data, and compared with Code ones. By means of fitting some empirical wind spectra, new expressions of power spectral density function for turbulent wind with higher precision were proposed finally.2. Four types of turbulent flow fields with different turbulence intensities satisfying uniformity requirements have been set up. Buffeting responses of three typical two-dimension bridge models, such as plate model, streamlined box girder model and two edged-beam model, were measured respectively, with acceleration sensors. By cutting off frequency of acceleration power spectrum to filter waves and obtain displacement variance. The results demonstrated that the data processing method can remove noise effectively, and variation trend of buffeting response with velocity is good.3. Six components aerodynamic admittance test was done on several representative bridge sections using cross-spectrum method. Based on the conception of equivalent aerodynamic admittance, not only the aerodynamic admittance of several different bridge sections were analyzed and compared, but also the influence of wind attack angle, wind speed, turbulence intensity, bridge guard railings on aerodynamic admittance were discussed.4. Buffeting response of bridge decks was calculated both in the frequency domain and in the time domain. The influence of self-excited force, wind speed cross-spectrum, buffeting force cross-spectrum, instantaneous wind attack angle on buffeting response was discussed. Based on computation model with six components aerodynamic admittance, the influence of different wind spectra on bridge sectional model about buffeting response was compared in detail. 5. The calculation results of buffeting response of bridge decks using spot-test aerodynamic admittance were compared with the experimental results, and the reliability and validity of spot-test aerodynamic admittance were verified further.