The Research On The Method Of Form-finding And Free Vibration Characteristics Of The Membrane Structure

The membrane structure has been a kind of new developed form of construction structure in the nearest dozens of years all over the world, and the form-finding is the first and the foremost procedure during the designing of the membrane structure. The purpose of the form-finding is finding out the initial shape and the distribution of stress. The selection of justified parameters has an important effect on the initial shape and the distribution of stress of the membrane structure. The pattern of the membrane structure is manifold, and the variation of the curved face is complicated. As a result, the analysis of the parameters for typical membrane structures is a significant work for the form-finding of the membrane structure.The characteristics of the membrane structure and main questions existed during the designing have been analyzed in the paper at first. Meanwhile the outcomes of the research on the methods of form-finding and relevant theory have been summarized. The paper has introduced the basic theory for the method of nonlinear finite element, and deduced the equilibrating equations for the membrane structure, which could pave the way for the research on form-finding of the membrane structure.Two typical membrane structures have been analyzed by universal software named ANASYS in the paper, what is more, the paper has expounded a more justified method for form-finding, in which the method of second form-finding and self-weight are considered. In addition, the differences of effect on the initial shape and distribution stress by the change of design parameters have been analyzed in the paper, and the paper provides us with an appropriate scope of the design parameters for two typical membrane structures, meanwhile the scope could be used for other familiar designing of the membrane structure. The paper has applied the method of form-finding to practical projects, and the paper has proved that we can obtain a proper initial membrane structure by the method mentioned above. The paper has expounded a new method for form-finding against the second tension to the membrane structure. What is to say, we can obtain initial curved faces through constrained displacement on the control points. The paper has applied this method to the construction simulation of the second tension to an assumed modal, and provides us a proper programme. The simulation of the second tension to project is convenient for us to put into stress control and analyze the construction inaccuracy effectively. Generally speaking, the method mentioned above is also valuable to be a reference for other projects.The general way of the analysis on free vibration characteristics of membrane structures neglects the effects of supported system, and such method may bring us with inaccurate results. The influences on the free vibration by the change of the stiffness of supported system and the prestressed force on cables and membrane have been analyzed in the paper. In addition, the analysis results show us that the free vibration is higher than the free vibration without considering the influence of supported system. Furthermore, the selection of the prestressed force on cables and membrane has great effect on the analysis of free vibration on the whole structure.