Study On Buffeting Control Measures For Construction Of Long Span Cable-stayed Bridges

Due to the constraints of economic development and other various conditions,the bridge structure has also continued to develop in the direction of large spans.In order to increase the span,bridges often adopt the method of reducing the weight of the main beam.Therefore,the flexibility of large-span bridges will be very large,and the stiffness and damping will also decrease,which will result in the structure becoming more and more sensitive to wind loads.The wind-destroying accident of the Tacoma Bridge in 1940 shocked the bridge engineers.From then on,engineers began to pay attention to the impact of wind power on the bridge structure.Long-span cable-stayed bridges generally use segmental cantilever construction methods.The turbulent wind will induce the buffeting response of the bridge structure.In the maximum double cantilever state during the construction phase,the structure has less rigidity and damping,and it is more sensitive to the effects of the wind.Therefore,the buffeting response caused by the turbulent wind during the construction phase is better than The bridging phase is much larger.Excessive buffeting will inevitably affect the construction and structural safety.Excessive buffeting response may damage the construction machinery and construction personnel,and may also lead to local fatigue.This article systematically studies the following aspects:1.This thesis takes the main bridge of Nanjing Fifth Yangtze River Bridge as the engineering background,uses the finite element software ANSYS to establish the full-bridge finite element model,and uses the frequency domain method to calculate and analyze the buffeting response of the bridge during the construction phase,using the industrial wind of Southwest Jiaotong University.The hole laboratory tests the three-component coefficient of the bridge section;under the excitation of the initial displacement,the flutter derivative of the bridge section is identified using the least-squares complex exponential method(abbreviated as LSCE method);combined with the identified flutter derivative,MATLAB software calculates and analyzes the buffeting response under fluctuating wind,and analyzes its influence under various parameters.2.Damping analysis of the bridge is carried out using vibration damping measures of the tuned mass damper.With single-freedom harmonic excitation as the research object,the effects of mass ratio,frequency ratio and TMD damping ratio on the DAF of the bridge-TMD system were studied,and the optimized parameters were applied to the actual bridge.Observe its damping effect.Studies have shown that the installation location,frequency,mass,and damping ratio of the TMD all have an impact on the damping of the bridge structure.Generally,the TMD is installed at the location where the maximum buffeting response occurs,and the frequency is set to the point where the response frequency spectrum power is maximum.The frequency corresponding to the point is used to control the buffeting of the bridge structure.The change of the TMD parameter has an important influence on the suppression of buffeting of the bridge structure.The greater the mass,the better the vibration damping effect.