Lightweight Long-span Structures Induced Vibration Characteristics And Vibration Control

With the development of economy and the progress of technology, the structural style of modern buildings becomes more and more complex, and the span becomes larger and larger. Along with the application of lightweight and high strength materials, this made developing of structural of modern buildings toward the direction of lightweight and long-span. And their fundamental natural frequency of free vibration may become closer to the frequency of human activities. As a result, obvious vibration of structures may appear due to human activities, which in turn, affects the human comfort.The main object of this paper is to analyze the vibration characteristics of lightweight and long-span structures due to walking, runing, jumping, rhythmic activities, standing up and other common human activities. The control theory and standards of vibration due to human activities for long-span lightweight structures are established based on the aspect of human comfort, which gives reference to the design of the similar structures and development of associated specifications in the future. Taking the long-span structure in South Railway Station of Changsha as the engineering background, the vibration of its waiting room due to human activities is analyzed detail. The main work and conclusions are detailed as follows:1,The natural frequencies, modal shapes, damping and other dynamics characteristics of structures are analyzed in detail, which includes:(a) the analysis method, the energy method and lumped mass method for solving natural frequencies, (b) the solution methods for damping like vibration decay method, resonant amplification method and half-power method, and (c) the comparison of the superiority or inferiority and application scopes between those methods.2,Loads caused by common human activities (short title Human-Induced Loads) are discussed in detail. The corresponding simplification of mathematic models, such as Fourier series model, impulse model and stochastic model are established and the Fourier series model is stressed in the present study. 3,Vibration control standards of long-span lightweight structures under common human induced loads are analyzed from the aspect of human comfort. In particular, International Standard ISO 2631-2:2003 and the vibration control standards recommended by AISC (American Institute of Steel Construction) are expounded explicitly.4,For those lightweight and long-span structures which not meet vibration control standards, optional vibration decreasing measures are provided. The application field and appropriate conditions of the vibration reduction measures are discussed in detail, and the vibration reduction principle and actual application of the tuned mass damper (TMD) are introduced especially.