Study On Wind-induced Vibration Response And Vibration Control Of Multi-rhombus Plug-in Steel Tubular Tower

Multi-rhombus plug-in steel tube tower has the prominent virtues of good Appearance, ease of construction,less bulk and less workload on maintenance,etc.It has been widely used as the primary pole styles for a long time in foreign countries and has been put into use in our country,and also will have a good future.Wind load is the most important load of steel tube tower,the wind-induced vibration is the uppermost factor having effect on structure design and work performance. Traditionally it is consumptive to withstand the wind vibration by strengthening the bearing structure,however, vibration control for the structure is a active,saving and effectual method.This paper aims at putting forward a "wind vibration damping control technique"to reduce the dosage of the steel,holding back the demolishments of steel tube towers and communication towers due to wind-induced vibration,and subsequently the execrable aftermaths of discontinuity in circuits and communications.Firstly,the theory of average and fluctuating wind load is expounded in this paper,also multidimensional inter-correlation artifical fluctuating wind loads acting on the tower are simulated and verified by M.Shinozuka method with random vibration theory.On the basis of being familiar with the conformations and provisions of the codes adequately, intension, dist-ortion,frequency and mode shapes are studied by using dimensional shell FEM model,then wind vibration time history analysis is studied by using the mode vectors and wind loads time history,employing the linear state space equation and MATLAB programme.In order to reduce the "wind vibration" and steel dosage,this paper chooses the Ball Vibration Absorber(BVA) to be mounted on the top of the structure to reduce the response of displacement after comparing various kinds of control equipments.The natural frequency formula and vibration differential equation of the BVA systems are studied with D'Alembert theory and kinetics equations ,the system's vibration control mechanism is also expounded by the SDOF displacement-loaded mechanics model.According to the dynamic equation of the BVA-Structure systems,the vibration control effect of the BVA is studied in time domain. To probe into the vibration-absorbing effect of the BVA,a measurement on the attenuation curves of the simulating-tower with and without BVA were recorded and showed that the damping ratio of the structure with BVA were three to five times of the original structure.Response analysis in the frequency domain is also studied by using random vibration theory,from two aspects of vibrartion-absorbing coefficient and equivalent damping ratio to study the effect of μ_d , λ_d ,ζ_d and φ_k1 to vibration control. From the relationship between damping ratio andfluctuation amplifying coefficient, the applied design method of the wind vibration control of the steel tube tower is constituted,the example showed that the control device has particular effect on structures of low damping and long period,all these conclusions can be applied to the engineering design directly.In conclusion, BVA overcomes the difficulty in installing mass pendulum and TMD and can provide the control force in any directions,increase the damping of the tower markedly. As a kind of dynamic vibration absorber of simple conformation,free of maintenance and little cost,the BVA can control the wind-induced vibration effectively and will have a good future in wind-induced vibration control of high-rise structures.This paper studies the wind vibration control of the steel tube tower by the numbers,the conclusions afford the theory foundations for the emendments and perfectments of industry codes,code for design of the steel structures and code for design of the high-rise structures.