Study On The Influence Of Deep Canyon Wind Characteristics On Buffeting Response Of Long-Span Bridges

With the development of national infrastructure,more and more large span bridges are being built in China,especially in the mountainous areas of western China.However,the terrain in mountainous areas is very complex and the wind characteristics are very different from those in the plains.As the wind field characteristics are strongly correlated with the wind vibration response of the structure,the wind resistance design of large span bridges in practice often relies on the wind characteristics parameters obtained from field measurements.Accurate acquisition of the real wind field characteristics at the bridge site is of great importance for the safety and relevance of the wind resistance design of large span bridges.This paper takes a cable-stayed bridge located in a deep canyon area as the research object,and studies the average and pulsating wind characteristics at the bridge site in different seasons,as well as the influence of wind characteristics and other influencing factors on the shaking response displacement and power spectrum of the cable-stayed bridge,in order to provide a scientific basis for an accurate assessment of the wind field characteristics and shaking response in the deep canyon area.The main research contents of this thesis are:(1)A cable-stayed bridge was used as the research object,and three observation stations were set up at different locations and different heights,and the measured data were collected for one and a half years for observation research.The mean wind characteristics include mean wind speed,mean wind direction angle and mean wind angle of attack,etc.,and the pulsating wind characteristics include turbulence intensity,gust factor,turbulence integration scale and pulsating wind power spectrum,etc.By comparing with the norms,the differences in wind field characteristics between the deep canyon area and the plain area are compared,indicating that it is necessary to carry out wind field observations in the deep canyon area.(2)The analysis of the buffeting response in the vertical,lateral and torsional directions of the main girder of the cable-stayed bridge is carried out using the full modal coupled CQC frequency domain buffeting analysis method.The effects of using different coherence functions,aerodynamic conductivity and pulsating wind power spectra on the buffeting displacement response of the bridge are investigated,and the differences in the root mean square and power spectra of the buffeting displacement response due to changes in wind field characteristics such as wind speed,angle of attack,turbulence intensity and turbulence integration scale are compared.