The Effects Of Characteristics Of Mean Wind And Fluctuate Wind On Long-span Bridge

Wind load is one of the typical dynamic loads on building structures, the effect of wind load upon long-span bridge structure has been concerned with the emergence of long-span bridges. The influence of some wind characteristics on the aerostatic and aerodynamic analysis has been researched in this thesis, the main contents are as following:1) The model of the spatial non-uniformity of wind speed has been established in the Cartesian coordinates. The influence of the charecteristic of horizontal non-uniformity of wind speed on the aerostatic behavior of the bidge girder is analyzed based on the established model. The results showed that the non-symmetric parameters and the size of wind field had a great impact on the displacement deformation of the main girder. The displacement deformation will be too large if the the charecteristic of horizontal non-uniformity of wind speed is ignored.2) The flutter derivatives of the Nan Jing Chang Jiang No. 2 bridge have been identified and the flutter critical wind speeds are caculated in the case of different initial attack angles by the method of decoupled forced vibration based on the Fluent software. On the one hand, the flutter derivatives were identified in the case of zero attack angle and compared with wind tunnel tests which verified the correctness of the numerical simulation in this thesis. On the other hand, the caculation result of the flutter critical wind speeds in the different attack angles showed that the initial attack angle has some influence on the bridge flutter stability, the bridge has a better flutter stability in the case of negative attack angle compared with the one in the case of the positive attack angle;3) Buffeting response of Yang Pu bridge deck and Run Yang Chang Jiang bridge deck was caculated in the frequency domain. The influence of the turbulent wind characteristics on the buffeting response was discussed. It was found that energy distribution of wind speeds spectra used in high-frequency domain affect the buffeting effects, the buffeting response value is reduced with the increase of turbulence integral scale when the horizontal and vertical wind velocity spectrum with spectra Von Karman spectrum are used.