Kuniaki ORITO

A Study on Shape-finding and Structural Analysis for Cable Structures

Eiji IWASAKI Masatugu NAGAI

In some cable structures and others, the cable slides on the supports or the other cables under construction, it is bounded on them when those structures are completed. Mechanical and kinematical behaviors under construction of such cable structures must be observed. On the other hand, problem of shape finding of cable structures is very important because shape of cable does not settle until acting self-weight, pre-stress and external load. There are many kinds of condition for shape finding. A condition of equal tension along the cable is realistically and importantly because of avoidance of slack due to unexpected load. This situation of equal tension is made provided that cable slide on the supports or other cables. This situation can be represented if the cable passes through the pulleies on the supports or other cables.
A cable element is developed in this study for flexible cable structures with pulley. This element is formulated by modified functional of variational principle and has the same features as usually finite element based on the displacement method in which displacements are unknown variables. A few numerical examples are to show the accuracy and efficiency of the proposed cable element with pulley.
In the new cable element with pulley there is following feature;
(1) Very accurate solutions are obtained if finite element equations are evaluated exactly by the numerical integration.
(2) Very flexible cable can be analized if a few elements only are used.
(3) The magnitude of sliding displacement between pulley and cable is unrestricted.
(4) The shape of the cable structure under axial load constant could be determined.