Study On Dynamic Characteristics And Mechanical Properties Of Irregular TLD

As a new type of damping device,TLD has been widely used in wind-induced vibration control of high-rise buildings.It is composed of one or more liquid storage tanks installed at the top of the building.When the building is subjected to severe vibration,the internal liquid sloshing will occurwhich could control the vibration of the building.When the frequency of internal water sloshing is close to the natural frequency of the main structure,the horizontal control force resulted from water sloshingwill react on the main structure and reduce its vibration response.At present,the application of TLD in engineering is mostly focused on regular rectangular or circular TLD system,while the research on TLD water tank with irregular shape or built-in irregular baffle is relatively lacking.CFD(Computational Fluid Dynamics)is a cost-effective numerical simulation method that can be used to simulate liquid sloshing in TLD.Therefore,CFD simulation technology is adopted in this dissertation to analyze and study the dynamic and mechanical properties of water tank TLD system with irregular geometry under the sinusoidal excitation at its bottom.Firstly,TLD systems with irregular internal horizontal baffle,liquid tank with trapezoidal shape and fan-shaped are selected for the study on their dynamic characteristics.Thefirst-order natural vibration frequency of liquid sloshing is theoretically deduced by applying the velocity potential theory method,and the solution for the analytical formula of the first order natural vibration frequency of water sloshing are obtained.The TLD system with irregular shape water tank is then numerically simulated by CFD method.Through the comparative analysis with the results of natural frequency obtained from theoretical analysis,the effectiveness of CFD method in this dissertation to simulate the dynamic characteristics of TLD system with irregular geometry is verified.In this way,different amplitudes in the sinusoidal excitation are applied at the bottom of water tank,the variation in the free surface wave height on the side wall of TLD,the control horizontal force and damping ratio of liquid sloshing are studied and analyzed through comprehensive comparison.The results show that with the increase in the excitation amplitude,the wave height of the free surface on the side wall the horizontal control force and the damping of liquid sloshing will also increase.From the amplitudes in the nondimension wave height of free surface at side wall and non-dimensional horizontal control force coefficient,the irregular water tanks with built-in irregular baffle in the Y direction is most affected by the excitation amplitude at the bottom,and liquid tank with fan-shaped is the less affected.It is also found that the damping ratio of rectangular TLD system with irregular built-in baffle is much larger than those at of pure liquid TLD tank with irregular shapes in this dissertation.