Force distribution in massive intersections of concrete structural members has long been a problem to solve in global analyses. A method has been developed, implemented and tested which gives results directly available for concrete design.
Offshore concrete structures are usually of large dimensions. The intersection of structural members, the thickness of which may vary from say. 5 m to several meters, may be massive. The computation of forces in these massive intersections has long been a problem to solve. The state of the art to compute force in structure mer∼bers is now to use Finite Element Analyses, which are used to establish the response of the structure, i.e. displacements and forces. If it is quite easy to cope with requirement (i), it is usually for more difficult to fulfil requirement (ii). The purpose of this paper is to present a computational method which allows the designer to use forces directly calculated within the intersection.
In the global model used for FEA, the meshing within the intersection is usually governed by (i) a technical requirement i.e. the meshing of the thinner concrete members joining at the intersection and (ii) an economical aspect : global models do not usually incorporate refinements which would result in too expensive calculations. There are usually to different type of calculations which are developed from the results of the global FEA, (i) the zooming technique and (ii) the "strut and tie" method. The zooming technique consists of refinement which is obtained by continuously decreasing the size of the meshes : the transition zone where the decrease of size mesh occurs needs to be included into the global model. In this transition zone, triangular or quadrangular elements (plane or shell) or prism or skewed tetrahedrons need to be used.
