Research On The Dynamic Characteristics Of Frame-supporting Tower

Chemical tower is a high-rise structure with large aspect ratio,low nature frequency and small damping ratio in petrochemical industry.With the increasing of the tower scale,the possibility of the occurrence of wind-induced vibration increases and threats the safety of the tower.Frame-supporting tower with displacement restrictor can decrease the vibration,but there is no standard to guide the design of this structure.In this paper,theoretical analysis,experiment test and numerical simulation are carried out to analyze the dynamic response of the structure.Based on structural dynamic theory,the computational model is formed.The testing model is made according to elastic similarity criterion;a non-contact excitation system is designed to vibrate the high flexibility model.This system can provide both random load and harmonic load.Through experiment and simulation,this paper studies the modal parameters and dynamic response of the structure.Results show that frequency and damping increases,mode shape becomes smoother after setting restrictor,the displacement and strain decreases under vibration;the height of the upper restrictor has the greatest influence on these parameters.The along-wind vibration of the tower is little influenced by damping ratio and stiffness ratio;the cross-wind vibration is affected little by stiffness ratio but is sensitive to damping ratio.The cross-wind vibration is largely decreased by increasing damping ratio.Under resonance,the cross-wind load is proportional to the nature frequency of the tower while the amplitude is inversely proportional to the damping ratio,so the changing of the frequency and damping must be took into account.The cross-wind vibration may aggravate when the frequency increases largely and damping ratio changes a little.This paper further studies the dynamic response of the structure and carries out two prediction model which can guide the design of the tower.Research in this paper provides guidance to the design of frame-support tower with displacement restrictor.