Analysis of cable structures

A numerical procedure has been developed to analyze complex 3-dimensional assemblies of substructures and cables. The procedure is applicable to guyed towers, flexible transmission lines, cable roofs or mooring networks. The computer program, which has been developed to analyze these composite structures, accepts arbitrary loads on the substructures but restricts the loads on the cable elements to gravity, thermal, or fluid drag effects.The algorithm is built around an efficient cable element subprogram. From given loads and given positions of the ends of a cable, the subprogram determines the complete geometry of the cable, its end forces, and its tangent stiffness matrix. The cable elements are connected together or to substructures nodes.The equilibrium configuration of the assembly is approached by successive iterations which decrease the imbalance of forces which still exist at each node at the end of the previous iteration. Special numerical schemes, which insure rapid convergence of the analysis, are presented.The computer algorithm is discussed in detail, and the simplicity and efficiency of the formulation is demonstrated by several examples. Very large displacements of the nodes and associated second order effects on the substructures do not present any difficulty as the imbalances and stiffnesses at each iteration are based on the geometry of the system at the end of the previous iteration.