Study On Vortex Induced Vibration Control Of Long Span Steel Box Continuous Girder Bridge By TMDI

Under low wind speed,large span bridges are prone to vortex-induced vibration,and its wind vibration control has always been an important issue.In this paper,the Chongqi Bridge is taken as the research object,and a new passive control method of wind vibration,i.e.the inertia tuned mass damper(TMDI),is studied to suppress the vortex-induced vibration of long-span steel box girder bridge deck.The main work of this paper includes:(1).Firstly,the finite element model of a single steel box girder bridge of Chongqi Bridge is established by using the finite element software Midas Civil,and the structural dynamic characteristics are analyzed,including the calculation parameters such as natural frequency,vibration mode and generalized mass required for vortex-induced vibration calculation.Based on the three-dimensional vortex-induced vibration theory,this method can obtain the amplitude of the full-bridge model according to the aerodynamic parameters and initial amplitude of the segment model,and compare it with the amplitude of the full-bridge vorte-induced vibration test to verify the correctness of the analysis results.(2).In this paper,a new type of passive control measure-TMDI is studied.This vibration control device is based on TMD by adding an inertial container.The calculation model of bridge structure-TMDI system is established,and its vibration absorption principle is introduced.The optimal frequency ratio and the optimal damping ratio obtained by the dynamic amplification coefficient and the fixed point theory are used to optimize the parameters of the TMDI-structure system.(3).The vibration reduction effect under the TMDI resonant model is studied,and the calculation formulas of the generalized displacement peak ratio,the equivalent damping ratio and the displacement ratio of the main beam of the steel box girder are obtained.The variation of these three parameters with α under different mass ratios is studied.(4).In this paper,the calculation method of bridge structure-TMDI system under nonlinear vortex force is proposed,and the parameters of TMDI are optimized.The optimal frequency ratio and damping ratio of TMDI under vortex force are deduced,and then the calculation formulas of displacement reduction rate,girder displacement,generalized displacement ratio and phase difference are obtained.(5).Based on the optimized TMDI parameters,the wind-induced vibration response analysis of the bridge shows that compared with TMD,TMDI can effectively reduce the static deformation of the spring and the stroke of the mass block while maintaining the displacement ratio of the main beam basically unchanged.For the steel box girder structure,it is easier to meet the spatial constraints by using TMDI.