The design of cable nets and light tenso-structures requires a non conven- tional mechanical analysis, due either to the various sources of non linearity (large displacements, unilateral behaviour of the cables, non conservative loads) and to the fact that the cable does not have a reference con¯guration (a cable is associated to in¯nite reference con¯gurations). As a consequence, the ¯rst problem that the engineer has to face is to determine the initial state of the structure under its own weight compatible with a set of ¯xed supports (the so called zero state). This problem is known as form ¯nding. The paper examines the Force Density Method for form ¯nding, proposing a generalization that uses the exact expressions of the equilibrium derived from the equation of the catenary. The method allows to obtain an exact con¯guration that may be used as a starling point for subsequent incremental non linear analyses. In the paper it is shown that the use of the exact equilibrium conditions leads to a form ¯nding method that is very similar to the FDM, but yields signi¯cant di®erences in the initial form when the weight of the cables is not negligible. Furthermore, the newly introduced force density parameter is dimensionless, and has a clear physical meaning.
|Titolo:||On the force density method for slack cable nets|
|Data di pubblicazione:||2012|
|Appare nelle tipologie:||1.1 Articolo in rivista|