| The direction of research and content of this thesis belongs in the category of vibration control for structures. The technique of vibration control for the structures includes: active control, passive control and hybrid control. As a primary method of passive control, seismic isolation is widely concerned by technical personnel of structural engineering in all countries of the world. By using isolation devices, the structures or structural elements is separated from severe ground motions induced by disastrous earthquake. Enormous reduction of earthquake energy transmitted to superstructures is so achieved. The isolation system primarily classified into two basic types: laminated rubber bearings and sliding isolation systems. Although it is a ripe isolation system, the former has relative high price and may produce effect of resonance; the latter is difficult to study because of its non-linearity in essence, though it has low cost and good adaptable ability. The problems of theory and application for practical projects about sliding control for responses of building and equipments in buildings under actions of earthquake are developed in this thesis as follows:1. Linear Model and Optimum Parameters for Responses of Vibration of Sliding Isolation Structures with Self-Lock MechanismThrough equivalent linear method, vibration equations for multi-story shear-type structures with self-lock Mechanism, equations of state and output of the system, the optimum design for rigid sliding isolation structure of single-degree is developed. Choosing equivalent stiffness and viscous damping as the design variables, the formula for variance of output of the system is proposed on the basis of control theory to configure the model of optimum design for finding the parameters in the sliding system. By using analytical methods, the optimum parameters are obtained.2. Study on Responses of Friction Pendulum System with Variable Coefficient of Sliding FrictionFriction Pendulum System is the sliding isolation system with a spherical sliding surface. Because it has the self-resetting function, the system does not need to attach the resetting and caging springs and has better practicality of projects than that of plate sliding isolation, and has good capability for isolating responses of horizontal acceleration. However, the FrictionPendulum System has stronger non-linearity than the other's, especially under the condition of macro-amplitude vibration. Although a few progress has been made by far, some problems are left unsolved.To make study convenient, the past researches on FPS simplify coefficient of sliding friction into a constant. But it is variable during the motion of the FPS slider. Based on non-linear vibration equations, considering the coefficient of sliding friction of FPS bearings as the function of the sliding velocity of the slider, response of earthquake of a FPS-isolated building subject to three different records of earthquake acceleration is studied by using tool of numerical simulations provided by MATLAB. The results indicate that it is feasible to predict the responses of FPS-isolated structures simplifying coefficient of sliding friction into a constant.3. Study on FPS-isolated Equipment in BuildingWith the advance of science and technology and the development of society and economy, more and more expensive and sophisticated equipments and instruments are installed in buildings. The problem of improving earthquake reliability of equipments in buildings seems more prominent than ever before.At present, dynamic floor system is generally used to isolate the precision instruments and computers locally. Such a system can reduce the response of acceleration of equipments to enhance its ability of overturn resistance. However, the system needs occupy relatively large building area, has high cost and is difficult to construct.The Friction Pendulum system is used to replace the dynamic floor system mentioned above in this thesis. The vibration equations of story and equipment are derived... |
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