الفهرس Only 14 pages are availabe for public view
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Abstract
Deployable structures are intelligent structures generally designed to undergo specific desired motions to meet practical requirements. Ease, speed of erection and dismantling procedures, and the possibility of reuse are some of their primary features which make them suitable for both temporary and permanent structures. They can be used for recreational purposes, or provide solutions for quick sheltering after natural disasters. A more recent application for permanent structures is the retractable roof structures employed to cover large areas, such as stadiums or tennis courts. In addition, it can be opened or retracted to provide a traditional outdoor venue under good weather conditions.
The basic unit of these structures is a construct called duplet. A duplet consists of two pin¬jointed bars called uniplets connected at certain intersection point by a pivotal, ”scissor”, connection. Each duplet is assembled and hinged at the four end points to end nodes of other duplets thus making up the large structure. The uniplets might be of straight, angulated or multi-angulated shapes.
To design a feasible retractable structure, two fundamental requirements have to be satisfied. First, the structure in its initial configuration must be able to be deployed. Second, a desirable, practical and visually pleasing configuration is produced when it is deployed. In order to obtain such type of be ha vi or, some specific geometric conditions have to be satisfied. On that regard, an in-depth study is carried out into the kinematical behavior of closed-loop retractable structures with different shapes of initial prescribed boundaries, structural configurations, member’s lengths, and end nodes arrangements. The observations of the study are then translated into a set of geometric rules necessary to maintain the feasibility requirements.
The study is done following a numerical procedure based on the force-method, to simulate the motion of structures during the deployment process. Wealth information of the structure’s staticlkinematic characteristics can be obtained from the equilibrium matrix assembled in the . force method. These characteristics are essential for the deployment computations. Thus, an approach is proposed to derive the equilibrium matrices of the two and three dimensional angulated uniplets. Then the equilibrium matrix ofmulti-angulated unipJet composed of more than two elements is computed through an elaborately developed numerical process. The . proposed approach is generic such that it can be successfully applied to obtain the equilibrium
, matrices of various types of deployable structures’ elements.
The studied retractable structures have their special displacement routes 111 deployed or folded into their desired/feasible shapes. Thus, the considerable prob14 structures is how to connect them to an appropriate supporting system which can their motion and maintain their displacement route to reach the final desired s~ clear figuring out of their displacement route and understanding their behaviq studied free of any presumed constraints that may affect their behavior. In ~ appropriate supporting system can be found. Hence, finding the supportingq inverse structural problem in which the configuration changes during deployqJ driving parameters in the process. During analysis, the resulting mechanisro~ contain combination of internal mechanisms and rigid-body mechanisms, ~
. .~.
absence of supporting system. Accordingly, it is necessary to introduce an al~
the rigid body mechanism components out of others.j
Two different supporting systems may be selected for retractable structu~ supporting systems have different effect on the motion of the structure. First,~ mounted on pinned columns thus allowing only for structure expanding.,;~ structure is supported on a number of certain fixed points thus allowing rigi41 while the structure is expanding. The kinematical behaviors of structures .., possible supporting systems are studied and explained in brief. .j.i~.:.,.
The numerical procedure is demonstrated through a computer program” author using MA TLAB and the program results are compared to the published •••
Covering is also another considerable problem to the retractable structurea.l achieved by replacing the angulated elements in the bar structure with cover .••• plates are connected by means of scissor hinges at exactly the same locations~ bar assembly. Thus, the kinematic behavior of the retractable structure rema” The structure can then, be deployed or ”closed” to form a covered enclosure. reveal a central opening space. A kinematical study is carried out to show the beIW plate covering system of retractable structures with different shapes.