Analysis And Experimental Study Of Seismic Performances For Latticed Shell Structures With Buckling Restrained Brace

In recent years, with the rapid development of large span spatial structure, the study of seismic performances of latticed shell structure is special important. The current seismic design method is to prevent earthquake action by enhancing the self stiffness of structure in order to satisfy the seismic fortification criterion. The main stressed members will go into elastic-plastic working stage when the structure encounters strong earthquake action, which will give rise to structural damage. Therefore, to increase the degree of safety of large span spatial structure and reduce the structural damage is one of the developmental directions of seismic design of large span spatial structure. In China, most of the regions locate at earthquake region, so the influence of ground motion should be considered in seismic design. Hence, it is great important theoretical significance and engineering value to intensively study the performances of seismic and vibration reduction of large span structure. From the above aspect, a kind of brace namely double-tube buckling restrained brace with contact-ring is proposed in this thesis, whose performances are analyzed in detail. Then applying control theory of structure, the idea of using the double-tube buckling restrained braces with contact-ring to replace partial members of original structure is propounded based on the force and structural feature of space latticed shell structure, which consists of the new type of reduction vibration system of latticed shell structure. The latticed shell structural system with buckling restrained braces has been analyzed. Some main achievements of the dissertation are described as follows:(1) A kind of new Buckling Restrained Brace namely Double-Tube Buckling Restrained Brace with Contact-Ring is proposed. It has many advantages such as light weight, convenient connection, high strength and stiffness at the connection segment. Therefore, it is very suitable to be used in large span spatial structure.(2) The simple caculated mode and stiffness equation of BRBs with Contact-Ring is established. On this basis, a program of elastic-plastic finite element analysis is edited by the language MATLAB, and applied to the caculation of bearing capacity of Double-Tube Buckling Restrained Brace with Contact-Ring.(3) Based on the theory of the finite element method, built the finite element entity model of Double-Tube Buckling Restrained Brace with Contact-Ring. The Double-Tube Buckling Restrained Brace with Contact-Ring is systematically analyzed. Then the strength, the stiffness and the dissipative characteristics of member are obtained.(4) Experimental study has been carried out on the basis of the existing results of finite element calculation, the baring capacity and the change law of load-displacement curve of member on the condition of loading are discussed. In the test on cycle load, the dissipative characteristics of Double-Tube Buckling Restrained Brace with Contact-Ring are mainly discussed. Moreover, the influences of the number of Contact-Ring, the gap and stiffness of outer shell on the hysteresis loop are discussed. Finally, the restoring force characteristics and simplified model of Double-Tube Buckling Restrained Brace with Contact-Ring are obtained,(5) Double-Tube Buckling Restrained Braces with Contact-Ring are introduced into latticed shell structure to replace partial members of that, which changes the stiffness and damping of replaced structure. The seismic ability of structure is heightened by the change of stiffness and damping, and the idea of mitigated motion for new structure is put forward according to the theory of structural control. The dynamic time history of latticed shell structure with Buckling Restrained Braces is analyzed with the common software ANSYS. The dynamic performances of single layer K6 type of latticed shell structure are studied. Then the laws of the dynamic responses of structural system under horizontal earthquake action, vertical earthquake action and three-dimensional earthquake action are analyzed, respectively.(6) The structural seismic performances under three-dimensional earthquake action are discussed when the Buckling Restrained Braces are introduced into structure. The peak values of internal forces and displacements of structure decrease, which prevents the individual members of structure from damaging prematurely, that is to say, the purpose that Buckling Restrained Braces yield firstly to dissipate energy in order to protect the main stressed members is obtained.