Prestressed membranes above circular and elliptical plan

This doctoral thesis deals with suspension cable roof structures above a circular and elliptical plan. The methodology of analysis is based on a basic annular cable roof structure of an external diameter of 70 m. The roof structure is designed as a prestressed membrane from the precast panels made from lightweight structural concrete which are supported with the bearing and prestressing tendons that are radially led between the two peripheral rings. The structural arrangement and the process of construction are described. The static system is specified and the terms like self-anchored system or equilibrium state are also defined. Finally, the results of static analysis are discussed in detail. The main aim of the doctoral thesis is to design a roofing of football stadium terraces using the structures of a basic annular cable roof; and present two alternatives – above circular and elliptical plan. The circular alternative comes directly from basic annulus, only the main dimensions of the new-designed structure are correspondingly extended. The elliptical alternative is an alteration of the circular design. As the radial tendons are anchored to the flexible peripheral curved girders, and the structures form the self-anchored system, the horizontal tendon forces load the peripheral girders radially. Because of that, it is essential to design a state of stress in tendon to prevent the undesirable global bending moments on the peripheral girders, and subsequently large non-uniform horizontal and vertical displacements of structure. Therefore, a study of the optimal load of ellipse is carried out. On the basis of the study, two basic requirements to structural arrangement of the elliptical roof are formulated. To illustrate the importance of a correct design, the optimal and unsuitable structural arrangements are compared. Finally, the results of static analysis of the circular and elliptical roof are again discussed in detail