The Research On The Whole Process Of Cable-nets Nonlinear Analysis

Cable-nets structures is an important form of tension structures system. Compared with traditional rigid structures, cable-nets structures have two distinct characteristics, One of which is geometry form is influenced by prestress, and the other is strong geometric nonlionearity in work phases. Consequently, the structural mechanics behaviors are greatly affected by structural parameters changes.Fistly, in this thesis , the nonlionear increment equilibrium equations are derived according to U. L formula, and the numerical course of nonlionear finite element method on form-finding are presented through the use of approaching control points displacement method. Secondly, by virtue of ANSYS, the form balancing the given prestress distribution and the geometric control parameters of several sample are found according to Newton ?Raphson method combined with BFGS method. At the same time, the course on form梖inding is to program adopting APDL. The results demonstrate that the method described above is practicable and practical. On accout of the form collaps caused by prestress distribution, the thesis discuss the influences of the self-weight and the initial prestress distribution on structure form stabilization and find out the main influence factor. On the basis of equilibrium form, the thesis discusses the influence of load distribution, load change, prestress change, single cable area chang and arrow height change on cable-net static behavior and finds out the main influence factor.In order to research dynamic behavior of the cable-nets strctures, the dynamic equilibrium equations and relevant mechanics matrixs are conduted according to Hamilton theory. Afterwrd, center-deffenrence method, linearity acceleration method , Wilson-θ method and Newmark-θ method are presented. So the dynamic finite element method is formulated. In order to research the sel-vibration characteristics on cable-nets structures,the thesis conducts Lanczos method solving self-vibration frequency and mode paticipation factor, secondly, the thesis researches sel-vibration characteristics of two cable梟ets structures. The results demonstrate that the vertical vibration is the main mode. At the same time, main cable area changes, assitant cable prestress diversifications, load distribution varieties , load indendity and large deformation dimino effect are taken into accountrespectively so as to discuss the vibration traits. The results reveal some rules on cable vibration. Through the analisys of seismic spectrum, the thesis discusses respectively the influences of damping, the numbers of mode expanded, the input directions and the large deformation dimino effect on the response of seismic spectrum. The results demonstrate that damping and large deformation dimino effect have great influences on spectrum characateristic of cable-nets structures. In order to reveal the transient dynamic behavior of cable-nets, the thesis erects increatment equilibrium nolinear dynamic equations with the course of solution, discussing the parameters on solution. Afterward, direction inputed of seismic recorders, dimino offect of dead load and structural parameters are taken into accout respectively, then a great many computations are taken. The calculated sequences reveal the rules of transient dynamic response about cable-nets structures. In a word, the study on cable-nets structures in the thesis has some advantages on actual engineerings.