A relatively simple element for the quasi-static analysis of marine cables is described. Although the element is based on the catenary equations, It has a finite element interface; that is, it is characterized by nodal displacements and forces which are related via a stiffness matrix. Therefore it is particularly easy to add to element libraries of existing codes. In addition, the element has a ‘self-discretization’ strategy, and hence can be used to model single branch cables of any length. An extensive investigation of alternative discretization and stiffness calculation schemes is presented, and conclusions are drawn as to the conditions under which the schemes are most appropriate.
Cables are ubiquitous in marine operations. While cables or cablelike structures are sometimes the primary components in a particular application, they are very often combined with, for example rigid or flexible floating bodies, or bottom-founded structures composed of tubular members, to form a composite system. Computational tools for the response analysis of such systems must therefore be able to model a variety of different components. Because of these differences between cables and other components, the numerical models and algorithms convenient for the response analysis of cables are not always easily integrated into the models and algorithms which more used for the analysis of the system. The objective of this paper IS to present a robust, efficient, easy to use, small, strain, elastic cable element which is completely compatible with the most common methodology used to determine the response of nonlinear structural systems, i.e., a displacement formulation of the equilibrium equations and (modified) NewtonRaphson solution procedures. As such, the element is not meant to compete with special-purpose "cable" programs. Rather, it has a displacement-based, finite element-like interface such that it can be incorporated readily into a general-purpose, finite element code for structural analysis.
