Research On The Mechanical Property Of TLD With Internal Baffles And Optimization Design Of Vibration Control For Wind-induced Tall Buildings With TLD System

Tall buildings are more susceptible to wind-induced motion due to their slender and small damping characteristics.Excessive wind-induced response will make residents feel uncomfortable,and easily cause structural fatigue and reduce service life.In order to control the wind-induced motion of tall buildings,Tuned Liquid Damper(TLD)is selected as an effective passive dynamic vibration absorber in practical engineering.As the viscous damping of liquid is very small,TLD system with pure water can hardly meet the requirements of windinduced vibration control objectives.Thus,internal energy dissipation components can be installed in the TLD system to improve the damping to solve this problem.Meanwhile,it causes the reduction of liquid sloshing frequency of TLD system.However,this reduction effect in natural frequency isn't studied extensively at present literatures.On the other hand,the anticipation of higher mode and the nonlinear modal coupling in the liquid sloshing will occur when the TLD system is subjected to large amplitude excitation,which resulted in the effectiveness of linear theory for predicting the liquid sloshing phenomenon in TLD.Since the large reduced-scale TLD model is hard to be made in the wind tunnel test on wind-induced vibration control of tall building with TLD system,the real-time hybrid test is an effective method to verify the vibration control effect of TLD system on tall buildings by experiment.As for the traditional earthquake shaking table,time delay effect in real time hybrid test is relatively obvious as result of the hydraulic actuator.So,it is also needed for the study on how to use the electric shaking table to conduct the real-time hybrid test on wind vibration control of TLD system on tall buildings.At the same time,the parameter optimization design of TLD system is also necessary in order to obtain better control effect.In order to explore the theoretical research of TLD system and its damping mechanism extensively,this dissertation takes the rectangular water tank with internal baffle as research object,the mechanical property of TLD with internal baffles and its optimization design for wind-induced vibration control of tall buildings with TLD system are investigated by the comprehensive and combined theoretical analysis,CFD numerical simulation and shaking table test methods.The real-time hybrid test is also adopted to study the vibration control effect of TLD system to wind-induced tall buildings.The parameter optimization design of TLD system is then studied to improve its efficiency on the wind vibration control effect.The main work from this dissertation is listed as the following:(1)Based on the potential flow theory,the formulas of equivalent linear damping of TLD with internal vertical and horizontal baffles are derived respectively.The formula is further modified to consider the shift in the natural frequency of liquid sloshing caused by internal baffles and the hydrodynamic interaction effect between the baffles.The effects of parameters such as water depth ratio,excitation amplitude,baffle number and baffle spacing on damping ratio of TLD system are analyzed.The effectiveness of the proposed formula is verified by shaking table test on TLD system with various configurations in internal baffles.At the same time,the applicability of the proposed formula is investigated by considering the influence of existing baffle on the liquid sloshing state.(2)Based on Faltinsen's nonlinear three-dimensional modal theory,the formula of nonlinear damping of TLD system with internal horizontal baffle and vertical baffles are derived by potential flow theory,then it is modified by considering the influence of internal baffles on the natural frequency of liquid sloshing respectively.The effects of water depth ratio,excitation amplitude,baffle length(height)and baffle position on the nonlinear liquid sloshing are investigated.The accuracy of the proposed nonlinear model is verified by the experiment and numerical method.The applicability of the proposed nonlinear model for TLD system with internal baffles is also investigated for various configurations in water depth ratio,baffle length or height.(3)Taking the third-generation structural control benchmark model as the example,three scaled rectangular TLD models with internal baffles in the form of 1 / 30,1 / 40 and 1 / 50 ratios are designed.By shaking table test and CFD numerical simulation method,the influence of model scale effect on liquid sloshing of TLD system is studied by comparing the wave height of the free liquid surface,base shear and dynamic liquid pressure at the same position under different excitation amplitude and excitation frequency.The results show that the model scale effect is hardly obvious on the value of wave height and base shear of TLD.(4)The Real-Time Hybrid Test(RTHT)platform with small linear electrical motor actuator is constructed by utilizing Lab VIEW,MATLAB/Simulink software and NI Compact RIO embedded system and shear sensor system.The platform breaks through the limitation of the high-rise building damping control system in the wind tunnel test because the scale model is difficult to reflect the dynamic characteristics of the prototype.It is suitable for the real-time hybrid test of various structures with damping control system,and has the advantages of simple operation and good accuracy.The effectiveness of the established RTHT platform is verified with good accuracy by comparing the time history of command(or target)velocity with that of measured velocity from the shaking table.The vibration control effect of TLD system with internal baffles on the third-generation structural control benchmark building under dynamic loading is investigated by the constructed real-time hybrid test platform.It is shown that there are good agreements between the real-time hybrid test and numerical simulation results for the wind vibration control of TLD system with internal baffles on this tall building.(5)The optimization design of TLD system with internal baffles for obtaining more vibration control efficiency on wind-induced tall building is conducted by the equivalent linearization damping theory.The optimal ratio between TLD and main structural system,the optimal damping ratio of TLD system with internal baffles are derived by structural optimization method.Taking a tall building and installed TLD system with vertical baffle as an example,the whole optimization design procedure for TLD system is conducted by including the secondary optimization results for the number,height and position of the internal baffles.The optimization results are further verified by the real-time hybrid test on the wind-induced tall building with optimized internal baffle configurations in the TLD system.