Editing Tensile structure (section)

=== Membrane materials ===

Common materials for doubly curved fabric structures are [[PTFE]]-coated [[fiberglass]] and [[Polyvinyl chloride|PVC]]-coated [[polyester]]. These are woven materials with different strengths in different directions. The [[Warp (weaving)|warp]] fibers (those fibers which are originally straight—equivalent to the starting fibers on a loom) can carry greater load than the [[weft]] or fill fibers, which are woven between the warp fibers.

Other structures make use of [[ETFE]] film, either as single layer or in cushion form (which can be inflated, to provide good insulation properties or for aesthetic effect—as on the [[Allianz Arena]] in [[Munich]]). ETFE cushions can also be etched with patterns in order to let different levels of light through when inflated to different levels.

In daylight, fabric membrane translucency offers soft diffused naturally lit spaces, while at night, artificial lighting can be used to create an ambient exterior luminescence. They are most often supported by a structural frame as they cannot derive their strength from double curvature.<ref>{{cite web |title=Sprung |url=https://www.army-technology.com/contractors/field/sprung-structures2/ |website=Army Technology}}</ref>

[[Image:IRB-7-MUDDY2.jpg|thumb|left|Simple suspended bridge working entirely in tension]]