| With the development of modern traffic engineering on cross line structure design requirements continue to increase,new bridges gradually develop into large span,slender and gentle features,as a suspension bridge system with relatively strong spanning capability,the natural wind buffeting problem of main girder will be highlighted,the fatigue vibration of the structure under long period will greatly shorten its normal service life.Therefore,it is necessary to make a systematic research on wind-induced buffeting control measures of long-span suspension bridges.At present,there are many kinds of control methods for the problem of structural vibration control,tuned mass damper is one of the most widely used passive control methods for mechanical vibration suppression on bridges.This paper takes a long span suspension bridge as engineering background,the buffeting responses of the main and transverse planes of the bridge under fluctuating wind are investigated by numerical simulation.Combined with the principle of vibration reduction,the key parameters such as vibration,displacement and acceleration of the main beam joints are controlled.Through the research work,the main conclusions are as follows:1、Random samples of natural wind are obtained by Cholesky decomposition.Through the ANSYS two development language(APDL)to realize the fluctuating wind load to the input and solution of bridge structure.The simulation results of the comparison of structure vibration characteristics and time domain buffeting that random vibration form of beam based order transverse bending and vertical bending mode dominates,TMD parameters of the design of the bridge should be the maximum value of the frequency response based on frequency.2、The linear damping TMD device is simulated by the ANSYS different types of elements,and the root mean square distribution(RMS)and the amplitude spectrum response of the controlled structure in time domain are combined.The design parameters of STMD(Single Tuned Mass Dampers)were determined by orthogonal test method,the sensitivity of each parameter were analyzed.The study shows that STMD does not change with the damping effect of monotonic quality and stiffness,the damping coefficient increases to improve the damping performance of structure.3、Because the bridge natural frequency is low,the TMD control to extract the relative displacement of TMD node and the corresponding node beam time history,combined with spring damping principle after the discovery of the bridge TMD has too large initial static displacement and has nothing to do with their own quality,based on actual engineering under damping spring preloading technology solved in numerical simulation vertical bending vibration in the initial problem of large amplitude control.4、Adjusting the frequency parameters of STMD to control the first two modes of the bridge,it is found that the effect of lateral vibration control is more obvious when the vertical vibration control takes into account the first two modes.Therefore,in actual engineering applications,the design of STMD should be based on the excitation frequency of the controlled structure and the corresponding frequency response degree.5、MTMD(Multiple Tuned Mass Dampers)is used to simulate the vibration control of the bridge,through the offset adjustment of damping device parameters and main structural frequency,aging adaptive structure for the MTMD parameters of the bridge also has a certain extent,the design of long period of wide frequency band can be applied to the bridge. |
