DEVELOPING FEASIBILITY FOR FOLDABLE THIN SHEET COVERINGS

摘要

When working with deployable mesh structures, where the resulting structure is a permeable mesh; it is necessaryrnto add a membrane to complement the covering. In most cases, fabric membranes are used due to their lightnessrnand because they can be folded along with the mesh. For temporary structures, this is an adequate solution. In contrast,rnfor permanent structures, using longer-lasting materials for sealing membranes would broaden the applicationrnrange of these structures.rnVarious authors have proposed to include rigid sheets within deployable structural meshes [1] [5] [6]. Amongrnthem, it is worth mentioning Emilio Pi?ero and his "unfolding hyper cubic stained-glass window." This systemrncombines a deployable structural mesh with glass sheets that fold in unison. It can shift from a flat surface to arncubic shape.rnFurthermore, if certain characteristics are conferred to these rigid sheets, they could take on a structural role andrncover spans without requiring any additional structural componens. [2]. These structural surfaces may be built sornthat they become deployable structures themselves. This paper seeks to analyze the possibilities through therndesign of a deployable thin sheet covering.A folding Aluminum Sheet Covering was developed (Fig. 1) in such manner that the structural component servedrnas a protection membrane as well. The supporting capacity, acquired by these thin sheets when folded into certainrngeometries can be used to stand structural loads. Likewise, the sheet’s geometry is utilized to ensure water tightnessrnwithout the need for sealing compounds or flexible joints. This paper seeks to prove technical feasibility ofrnusing thin sheets for constructing deployable coverings, where the sheet can take structural loads.rnThe design of an 853 m2 covering, 24 m long x 5.56 m wide, made up by six independent modules was undertaken.rnEach module is folded from an initial size of 24 m to a final size of 4.6 m (figures 2 and 3) using an motordrivenrnsystem for dragging the wires. The chosen geometry produces an oscillating movement during folding andrnunfolding. To counter this problem, a traction and guidance system was developed so that it absorbed the rotatingrnmotion generated by the sheets as they are displaced.rnTwo mobile joints were also developed: One for high edges provided with a continuous geared-type hinge thatrncan also produce a water tight gasket. The other one, for low edges, is provided with independent hinges. The latterrnachieves water tightness thanks to a gutter generated by a fold on the sheet that guides water out of the joint.