Abstract:
|
Nowadays, cable structures are gaining prominence in civil engineering against the
traditional constructions thanks, among other reasons, to their lighter, to a better
optimization of the material mechanic properties, the saving of material or its great
beauty.
Despite the great advances in recent decades in the creation of new processes,
software and models for the design and analysis of cable type structures using in most
cases the Finite Element Method, still remain major problems in these processes due to
the flexibility of the cable elements and the need to settle the length of the cables and
the possible large nodal displacements.
This work deals with the main aims of the understanding those problems for the most
important cable type structures shape finding and structural analysis, at the same time
that the features of those structures, mainly the cable-stayed bridge and the suspension
bridge, and their relation with the analysis using F.E.M. are understood and analyzed.
All have been possible thanks to the realization of three examples, two proposed by
Dr. Iwasaki and a model of an actual cable-stayed bridge using for all of them the Finite
Element Method software, comp++. This program developed in the Department of Civil
and Environmental Engineering of The Nagaoka University of Technology, provides the
great advantage of have implemented a new concept of pulley that suppose a major
advance in resolving the cable structures shape finding and structural analysis
problems.
After complete the exercises, can be done several reflections about the efficiency,
accuracy and easily of F.E.M. in the execution of shape finding and structural analysis of
cable type structures. And, what is more important and original, the importance of the
new concept of pulleys from Dr. Iwasaki and Dr. Dang, crucial in controlling the length of
the cables sliding through them, and in the settling of nodal coordinates.
Making, thanks to the new developments, the shape finding much simpler and
intuitive, through the possibility of impose restrictions and assumptions of
displacements or pre-stresses in cable elements and pulleys.
The main interest of this new developed system of pulleys is that, after one step of the shape finding, the results can be used to the next step, or them can bind into nodes
and continue applying new loads with the structural analysis, which was not possible in
this way before these important advances. |