May 05, 2008
Abstract
This thesis deals with the techniques used in the numerical analysis of cable roof structures. These structures are usually very light and flexible and require analysis methods, which take their non-linear behaviour into account.
An extensive literature survey, concerned with both practical and theoretical aspects of cable roofs, is presented. Some aspects included are: structural systems, roof erection procedures, different cable types and their properties, structural details, roof loads and analysis methods.
As the initial shape of a cable roof depends on the internal force distribution, it cannot be described by simple geometrical models. Special iterative methods, usually not familiar to the structural engineer, have to be utilised in order to find the pretensioned configuration of the roof. The simple force density method is presented in detail and applied to a number of different types of cable roof structures. The method worked well for structures composed of only cables, but not for structures with compression members.
Three analytical finite cable elements are presented. Two elements are mathematically exact and can accurately model both taut and slack cables using only one element per cable. It is shown that the analytical elements are advantageous in modelling cable behaviour.
A static analysis of the Scandinavium Arena in Gothenburg has been performed. The results from this analysis were compared with results from the original design of the same object. It was found that the bending moments in the supporting structure—the concrete ring beam—were very sensitive to its shape. This explained the large discrepancy in the bending moment distribution between the analyses.
Results from a simplified method, used for preliminary calculations, agreed well with those of the more accurate finite element calculations, for a studied symmetric load case.
Failure stage analysis of the class of self-stressed cable structures called tensegrity structures has been identified as an area of further research.
Preface
The research work in this thesis was carried out at the Department of Structural Engineering, Structural Mechanics Group, at the Royal Institute of Technology in Stockholm, under the supervision of Professor Anders Eriksson. The work reported in this thesis was financed through a personal grant from KTH.
First of all, I express my gratitude to my supervisor Professor Anders Eriksson for his scientific guidance and valuable advice. I also thank Docent Costin Pacoste for help with the selection of a suitable beam element for the static analyses.
I would also like to thank Professor Emeritus Alf Samuelsson at Chalmers University of Technology in Gothenburg and Mr. Nils Dahlstedt, Technical Manager at the Scandinavium Arena in Gothenburg, for the valuable information about the Scandinavium Arena.
Finally, I am grateful to all people at the Department of Structural Engineering that have helped me in the work with this thesis.
Stockholm, April 1999
Gunnar Tibert
