November_1970 — Page 24

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Fig. 6

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Fig. 9

Fig. 11

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Fig. 8

Fig. 10

found in domes, because, a pyramid has no maximum ground area and can be peripherally enlarged unlike a dome.

To achieve maximum versatility, the standard UFP component should be equally useful in parallel and radial structures, as well as in combinations of both (Fig. 10). In this combination, an irregular star assembly (shown en- larged in Fig. 11) provides the transi- tion between parallel and radial sec- tions. Using similar constructions more complex ground plans can also be covered with UFP structures.

UFP structures combine, at the user's option, the advantages of folded plates, space frames and post-tension- ed structures. Thin plates easily de- form, but when folded, the planar portions restrict the deformation of each other by utilising their maximum stiffness, as external loads are resolved into components acting in the planes of the plates. Folding a sandwich panel is particularly advantageous in view of the properties of the lightweight mate- rials often used in sandwich construc- tion.

Buckling resistance is also increased by folding, because bending stresses are maximum at the fold lines where stiffness is greatest and where stress conditions are the same in the two opposing skins (i.e. both are in tension or compression).

The limited angular stiffness of single skin UFP structures requires that transversal tie rods be secured to their obtuse corners to maintain the desired fold angle (Fig. 12). Assem- blies of other component types may also have similar tie rods to convert

Far East BUILDER, November 1970