The Two-Dimensional Deployable Circular Roof Structures

Deployable structures is a generic name for a broad category of expandable structures that can be transformed from a closed compact configuration to a predetermined, expanded form, in which they are stable and capable of load bearing. Due to these characteristics, deployable structures which can meet the special requirements, catch the universal attention in the fields of outer space and civil engineering. Deployable structures usually include four major categories, foldable structures, inflatable structures& cable-membrane structures, tensegrity structures and retractable structures. The last three categories have wider applications in the field of civil engineering, but foldable structures are basically in a state of blank. Therefore it is necessary to research foldable structures. This paper presents the two-dimensional deployable circular roof structures, which are developed from foldable structures and retractable structures.Deployable structures have a basic feature that they can be folded reliably, in the process of folding, system is amechanism. the core of problem is the geometric form. First, the paper launched a study on the geometric form of two-dimensional circular roof structures. Through deduction of the geometric properties for developable element (including the straight rods element and angulated element), the multi-angulated rods were considered as the basic modules of the two-dimensional deployable circular roof structures. Based on that, a geometric topology model of the two-dimensional deployable circular roof structures has been constructed, and its deployablity has been argued. It also explored the possible support forms on the boundary.As retractable roof structures, their structural properties are focus of the study in the paper. First, the author replaced the"rods"of the multi-angulated rods with three kinds of trusses, and raised three categories of structure scheme. After comparing, the "arch scheme" in which the section features are changed at different positions of the truss has been considered as the optimal structure scheme. Second, the basic mechanical properties of "arch scheme" have been analyzed, also how the bar section, Structural highness influence the structural stiffness, the relationship between structural spans and weights of steel were discussed. Study results show that the structures in this paper are in control of structural stiffness. When the structures spread to a certain degree, structural stiffness is decreased significantly. When the span is larger, the paper raised a progressive measure that there are two railways in a structure to improve the structural stiffness.Finally, the optimization problem of the roof slab shapes has been explored. First, objectives of optimization design which request minimum clearances of roof plates, roof plates can't collide each other, and the max expanding area has been established, further more the author has compiled optimization procedures according to mini-max algorithm in virtue of software MATLAB. Second, the roof slab shapes of two-dimensional circular deployable structure have been optimized, after simulating the deploying process of roof slabs, we gained the conclusion that the method is feasible. In addition, the connection between the roof slabs and the main issues have been discussed, a constructional scheme of diagonal has been created.