Bird's Nest-type Cable Dome Structure Theoretical Analysis And Experimental Research

Cable-dome structures, composed of both cable in tension and struts in compression, are a class of flexible structures in tensegrity. On the basis of being prestressed to provide structural stiffness, this type of structures, featuring in light weight, giant span and verified structural styles, etc. has been regarded as representing the high level of giant-span spacial structures. The major two types of cable-dome structures being widely researched throughout the world are GEIGER and LEVY, both of which have been practiced in real projects and have therefore been mature in both theoretical researches and practical experience. The bird-nest cable dome structure analyzed in this article is a special type of cable domes, which has been rarely recorded up to now in any documents or references concerned. Combined with the components of this structure, this article commits itself to systematically researching and analyzing the bird-nest cable dome structure through both theory and practice on such areas as the distributions of initial prepress, the characteristics of both static and dynamic forces, the analyses in earthquake response and construction schemes. At last, this article testifies all the theories raised and conclusions drawn by experimenting on specific models designed and processed on this purpose.First of all, based on the relevant references both in China and abroad, this article reviews cable dome structures in its developing history, the practical appliances in engineering constructions, the existing conditions of both domestic and foreign researches in this area. Combined with the characteristics of bird-nest cable dome structure, the first chapter outlines the major theories to be testified and raises the focus one based on which there develop the supporting theories and case studies in the following chapters.Chapter 2 analyzes the features of geometric component in bird-nest cable dome structure and put forward the theory that besides the distributions of non-grid-jumping structures, there are possibilities to set up annular cables and masts according to the featuring forces of stress—the structural style of gird-jumping distributions, which could adjust the density of the grid distributions and could therefore optimize the distributions of the interior forces of the masks. On the basis of this theory, the article raises the simplified. calculating method in the distributions of initial prepress and deduces the general expressive equations of prepress. Through comparison and analyses in both calculation patterns and computerized calculations, the results demonstrate that the structural style of gird-jumping distributions, being precise and practical, could be effectively applied on practical constructions and could function as a useful complement in theoretical analysis.The analytical researches of static force in bird-nest cable dome structure functions as the basis for further researches and assessment in structural patterns. Chapter 3 hereof analyzes, through the pattern of grid-jumping and non-grid-jumping in bird-nest cable dome structure, the force-bearing and position-changes of both cables and struts under either full-span load or half-span load. The impacts on the performance of force-bearing being subject to the changes of prepress have also been considered hereby.Chapter 4 analytically researches the patterns of both grid-jumping and the non-grid-jumping in bird-nest cable dome structure concerning their respective self-vibration frequency and characteristic distributions of vibration types. It calculates and analyzes on the same time, the impacts on the potency of dynamic forces exerted by the prepress-levels, which could be influenced too by the sizes of the sections of annular cables. The results show that the structure performs well in terms of stiffness, speaking of which, the grid-jumping patterns performs weaker than the non-grid-jumping patterns.Chapter 5 focuses on the performances of both grid-jumping distributions and non-grid-jumping distributions in terms of earthquake response, which includes analyses in both internal forces of the components and the time-history patterns of position-changes. On the same time, it analyzes the influential roles played by the prepress on the structures' anti-earthquake capabilities. Researches hereof demonstrate that the whole patterns of the structure perform well in anti-earthquake functions.The construction schemes of cable dome functions as one of the decisive steps in the force-bearing capabilities of the structures. Chapter 6 hereof devotes itself in multiple tensegirty experiments in bird-nest cable dome structure through the method of dynamic relaxation, the process of which follows and simulates the construction schemes whose characteristics demonstrated in the procedures have also been analyzed.Chapter 7 focuses on the real model of the bird-nest cable dome structure (diameter=5.0 meter), which was designed and produced on the basis this article's theories. All the experiments conducted on this model verify the validity of theories contained through the following tests: the distributions of prepress in the structure; the analyses in the responses under multiple conditions of force-loads; the self-vibration frequencies under multiple conditions of prepress. Simulated on the same time the schemes of constructions, the experiments analyze and illustrate the reasons that give rise to the errors in the experimental data.Last but not least, this article generalizes all the research results contained and throws light in research approaches hereafter.