Numerical Simulation Of Extreme Wind Field And Wind-induced Vibration Of Suspension Bridge

With the increasing of bridge span,its stiffness and damping declined because of high slenderness ratio.The suspension bridge is a long-span flexible structure,and the wind stability has become a critical control factors which affect the design of suspension bridge due to its sensitivity of wind action.The suspension bridge is the structure in the atmospheric boundary layer,vibration response will occur under conventional wind or extreme wind,and even cause structural damage.Therefore,it is necessary to analysis wind-induced response of suspension bridges for the perspective of economic and security.Firstly,extreme wind field simulation and analysis of natural vibration of suspension bridge are proceed in this paper,and then the flutter analysis and along wind response analysis of the suspension bridge are proceed.The main research work includes:1.Based on Deterministic-Stochastic Hybrid(DESH)model,average wind speed samples of spatial points are simulated by Wood vertical wind profile model and Holmes horizontal radial wind profile model,and fluctuating wind speed samples with time correlation and spatial correlation are obtained by AR model,then downburst wind field with spatial correlation is obtained.2.According to Shi Yuan typhoon spectrum,the typhoon Prapiroon wind spectrum and the typhoon Sally wind spectrum,fluctuating wind speed samples with time correlation and spatial correlation is obtained by AR model,then typhoon wind field with spatial correlation is obtained.3.The approximate analysis method of nature vibration of cable structure is proposed by energy variational method.The natural frequency formulas for lateral vibration,vertical vibration and torsional vibration of the suspension bridge are derived,and they are compared with the results of finite element method.4.The theory of self-excited forces and flutter derivatives of the ideal plate are introduced,and 2D coupling flutter equation is established.Scanlan’s method and the reduction method are adopted for solving 2D coupling flutter equation.The critical flutter wind speed and critical flutter frequency of simply supported beam model are solved,and they are compared with the analytieal solution,the calculation accuracy of the two methods is analyzed.5.The flutter of the Humen Bridge,Jiangyin Yangtze River Bridge and the Yangluo Yangtze River Bridge are analyzed,the critical flutter speed of suspension bridges are obtained with different damping ratio,the affect on the critical flutter speed by damping ratio is analyzed.6.The conventional wind field,downburst wind field and typhoon wind field of Humen Bridge are simulated,the wind load is calculated,and it is applied on the finite element model to obtain the structural response.The affect on the natural vibration and wind-induced response of suspension bridge by setting anti-wind cable is studied.