Abstract
In recent years, a new type of hybrid dome structure called “suspen-dome” has become popular. The suspen-dome system is evolved as a combination of two structural systems, namely a single-layer dome and a cable-dome. This marriage of the two systems has proven to be highly successful, making it possible to combine the advantages of both systems. The upper part of a suspen-dome consists of a single-layer rigidly-jointed lattice dome and the lower part consists of a system of cables that are connected to the upper part of the dome by a series of struts. In fact, a suspen-dome is a double-layer lattice system. However, it is more economical, as well as, more visually attractive than a conventional double-layer lattice dome. In a suspen-dome the elegance of slim cables at the lower part makes the whole structure appear less crowded, allowing the beauty of the pattern of the upper single-layer part to stand out. Despite the increasing interest in the use of suspen-domes, the research into the behaviour of these domes is rather limited and there are no commonly acceptable procedures for their design. Hence, one of the main aims of this study is to provide a methodology for the analysis and design of suspen-domes. Another important objective of this work is to carry out an in-depth study into the behaviour of suspen-domes. In general, due to the rigidity provided by the upper single-layer dome, the geometry of a suspen-dome has an initial stable shape. However, for a suspen-dome to become a fully functional structural system, appropriate levels of prestress forces in the cables at the lower part of the dome are required. In this work, a thorough study is carried out for evolving a simple method of determining prestress forces. A proposed method is then presented in detail and exemplified using a finite element model of a suspen-dome structure. It is shown that the method works well and is effective in enhancing the performance of suspen-domes. To study the behaviour of suspen-domes, the linear and nonlinear response of three different patterns of suspen-domes with three different rises and spans under a combination of four different loading conditions, are examined. It is found that the functionality of prestress forces within a suspen-dome system is vulnerable when the system is exposed to unsymmetric loads. To overcome this issue, a new efficient way of adjusting prestress forces is proposed which is proven to be both simple and effective. One of the main achievements gained from the study of the behaviour of various suspen-dome test cases, is the realisation that these structures display a low degree of geometrical nonlinearity. In the structural system of a suspen-dome, when the system is stiffened by the application of appropriate prestress forces, there are clear indications that the behaviour of the structure is almost linear. This matter is discussed in Chapter 6. This will give designers the ability to estimate the behaviour of suspen-domes under the effects of loads by simple linear analysis.