| Non-platform-column shelters, with long span and large column distance, has been widely applied to the construction of new-era train stations. Due to the modern appearance, transparent vision and comfortable to use, this type of shelters has been recognized by both the public and the profession. This thesis has focused on the truss string structure, which has distinctive features and wide application prospect in future non-platform-column shelters. An intensive study on the static performance, stability, seismic performance, wind-resistance performance and progressive collapse behavior of the truss string shelter has been carried out. The results offer new methods and solutions for the analysis design of the truss string shelter. Some instructive rules and useful experience are summarized for the future design.Chapter1introduces the origin and application status of the non-platform-column shelter in China. The mechanical characteristics and advantages of the truss string structure are presented. An review on the present study of the truss string shelter is given.,The main research work of this thesis is briefly introduced.Chapter2systematically builds up a theoretical analysis method for truss string structures used in non-platform-column shelters. Analytical expressions for the internal force and displacement of the structure are achieved, which are applicable to many common load cases, including symmetrical distributed load, anti-symmetrical distributed load, half cross distributed load, temperature load and pretension load. The static behavior of the structure is analyzed according to the theoretical expressions, and methods to improve the static performance are also researched.Chapter3analyzes the failure model, stability and the related parameters of the non-platform-column truss string shelter. Importance is put on the influence of the torsion stiffness of the spatial truss string system on the structural stability The research gives the reason for the torsion stiffness improving structure stability, and then puts forward methods for enforcing the structural torsion stiffness. Besides, this chapter also studies the effect of the attached truss on restricting the primary truss failure, and the influence of the member yield on the structural integral stability. Chapter4analyzes the free vibration characteristics of the non-platform-column truss string shelter. The structural response under horizontal and vertical seismic is calculated, and then some simplified methods for the structural seismic design are researched. Finally, the relationship between the structural longitudinal dimension and the travelling wave effect is studied.Chapter5determines the wind-load shape coefficient of the shelter by simulations. Formulas for computing of the wind-load shape coefficient are fitted according to the simulation result. The wind-induced dynamic responses of the structure are also analyzed, and then the wind vibration coefficient is obtained. Based on these, the structural performance under multi-level wind load is analyzed and the structural failure models is identified. The structural mechanical characters under wind load is summarized.Chapter6takes Beijing north station as an example. The sensitivity of the structural elements is analyzed by the alternate path method. The response or collapsed process after failure of the sensitive members is simulated, and the possible collapse models is concluded. Two methods to prevent the progressive collapse of the structure are worked out, and both of them have been applied to Beijing north station successfully.Chapter7summarizes the main works and conclusions of this thesis, and also points out some further and meaningful works which may be done in the future. |
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