Study On Buffeting Response Analysis And Prediction Method Of Long-span Bridges Based On Integrated Transfer Function

The research history of buffeting analysis theory has been reviewed in this dissertation,the calculation method of buffeting response of long-span bridges has been summarized while the shortcomings in current research have been pointed out.Based on the three-dimensional buffeting analysis theory,the three-dimensional two-wavenumber buffeting force and response have been derived.The concept of integrated transfer function has been introduced and a direct calculation method for the buffeting response of a long-span bridge based on the integrated transfer function has been proposed.The characteristics of the integrated transfer function are studied and its effectiveness in predicting buffeting response are verified through both experimental and theoretical analyses.The main contents of the dissertation are as follows:1.The research history of buffeting analysis theory is reviewed.The research status of aerodynamic admittance function and the spanwise correlation of buffeting force are discussed.The main calculation methods of buffeting response of long-span bridges are summarized.The potential problems in current research and improvement needed in the existing calculation methods are discussed.2.Based on the traditional three-dimensional buffeting analysis theory,the buffeting response of structures with spanwise infinitesimal span trip,finite span section,and large aspect-ratio span are derived.The two-wavenumber joint acceptance function considering the three-dimensional effect of turbulence is defined,the concept of integrated transfer function is introduced and its identification method through sectional model experiment is determined,and a direct calculation method for the buffeting response of a long-span bridge based on the integrated transfer function is proposed.3.A set of devices is designed to measure the buffeting response of sectional models with different aspect-ratios.For the two structural sections of airfoil and streamlined box girder,the vertical and torsional integrated transfer functions are identified through the sectional model wind tunnel experiments.The effects of the ratio of the turbulent integral scale to the model width and the aspect-ratio on the identification accuracy of the integrated transfer function are systematically analyzed,and the applicable conditions of the strip assumption are expanded.4.The prediction results of buffeting response of airfoil structure,which based on the integrated transfer function identified through the sectional model experiments,are compared with the theoretical calculation results,and the precision and effectiveness of the integrated transfer function in predicting the buffeting response of long-span bridges is verified.The prediction results of buffeting response of streamlined box girder are also compared with the experimental results of the full-bridge aeroelastic model wind tunnel tests,which is widely used to obtain the buffeting response.The feasibility of the prediction method of sectional model expriment based on integrated transfer function is verified.5.As the background of a long-span suspension bridge,a full-bridge aeroelastic model buffeting response test is conducted to identify the the integrated transfer function.The influence of wind field parameters on the integrated transfer function was analyzed.The integrated transfer function of the bridge model identified by test in one turbulent field is used to predict the buffeting response of the same bridge model in another turbulent field.Comparing the prediction results with the experimental results,the effectiveness of the proposed method to modify the deviation of structural buffeting response caused by the error of wind field simulation parameters is verified.