Study On Buffeting Response And Static Wind Stability Of Double-Layer Steel Truss Cable-Stayed Bridge

Transportation power,railway first,railway plays an important role in our country’s economic development,long-span highway and railway cable-stayed bridges develop rapidly,and steel trusses have good wind resistance performance,gradually becoming the main beam structure of this type of bridge.Therefore,it is of great significance to study its wind resistance performance to ensure the bridge structure and traffic safety.In this thesis,a double-deck steel truss cable-stayed bridge with a main span of 425 m in the upper reaches of the Yangtze River is taken as the research object,and the buffeting response and static wind stability are studied by numerical simulation methods.The main research contents include the following aspects:(1)The development of cable-stayed bridges is introduced,the research status of buffeting response and static wind stability are reviewed,and the main research contents of this thesis are expounded.(2)Using ANSYS APDL language to establish a whole-bridge space model,the elastic modulus of the cable-stayed cable was corrected according to the Ernst formula,the elastic modulus before and after the correction was compared and analyzed,and the model was calculated by Lancozos method,focusing on the analysis of the first ten selfresonant frequencies and mode shapes.The results show that the fundamental frequency of the bridge is 0.166 Hz,and the first two orders are all side bending modes,indicating that the lateral stiffness of the cable-stayed bridge is weak,which conforms to the characteristics of long-span cable-stayed bridge.(3)With the help of MATLAB platform,the improved harmonic synthesis method is used to introduce fast Fourier transform and Hermit interpolation to simulate the threedimensional wind field considering the main tower effect,and verify the accuracy of the simulated three-dimensional wind field from the aspects of power spectrum and correlation coefficient.The results show that the improved harmonic synthesis method can accurately simulate the three-dimensional wind field of the main tower effect.(4)The ANSYS APDL language was used to write a bridge buffeting response calculation program to analyze the influence of different wind speeds and wind attack angles on the bridge buffeting response.The results show that the displacement of the middle of the span is greater than the displacement of the beam end,and the displacement at the far tower of the main beam is greater than that of the near tower,and the cable force is also greater than that of the near tower.With the increase of wind speed,the buffeting response gradually becomes larger and shows an exponential growth trend.As the wind attack angle changes from negative to positive,the buffeting response gradually increases,showing a nonlinear growth trend.(5)On the basis of considering geometric nonlinearity and load nonlinearity,the static wind stability analysis is carried out by the incremental-internal and external double iteration method;The wind vibration coefficient is introduced,the equivalent static wind load is calculated by the GLF method,and the ANSYS APDL language is used to write an iterative program for static wind stability analysis,and the two methods verify each other.Furthermore,the method proposed in this thesis is used to analyze the static wind stability of cable-stayed bridges at different initial wind attack angles.The results show that the static wind stability analysis method proposed in this thesis has high accuracy,and the vertical and lateral displacements and torsion angles of the main beam span show nonlinear growth with the increase of wind speed.The initial wind attack angle has a great influence on the stability of static wind,and the stability is enhanced when the wind attack angle is negative,and the stability is weakened when the wind attack angle is positive.