The Nonlinear Finite Element Analysis Of Cable Structures

Currently, the suspend structure is widely applied to bridge and house construction which can meet the needs of span with its multiple forms and flexibility. As the increasing complex of suspends structure and the forms of load, multiple methods of analysis have been proposed. This paper firstly introduce methods of suspend structure analysis, usually classifying into Analysis and Finite Element. The Analysis only applies to those simple structure and load, while Finite Element, the common method for suspends structure, is frequently adoptive to any structure and load forms, as of which the element model option gives directly impact on the calculation results. This paper then introduces the main cable units model, focus on two-node element model (including two-node straight-line element, two-node parabolic cable element model and two-node catenary element model) and multiple-nod isoparametric element model (including three-node isoparametric element model and five-node isoparametric element model). Finally this paper makes a comparison among multiple element models based on exposition of sorts of displacement models and form functions. On the basis of the advantages and disadvantages of existed element model, this paper proposes four-node isoparametric cable finite element model through widely absorbed in relative literature. The paper, applying cubic multinomial to displacement function, deducts the expression of form function and geometrical relation of elements on Lagrangian axis. Then the element equation and unit tangent rigid matrix are deducted on the basis of description of UL coordiate and principle of imaginary, the balance equation and overall tangent rigid matrix are integrated via introduction of terminal condition, and the nonlinear equation group is finally parsed on the basis of combination method of Newton-Raphson and increment. Bases on Fortran 95 standard language and the above theory, the paper compiles the finite element program, applies the program to the analysis of small dip cable structure, large dip cable structure and cable network structure, and then compares this results with other reference literature. The result indicates the quickness, preciseness and effectiveness of the above method, which is available for cable structure analysis and cable design.