Tensile

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Tensile

  1. 1. An Intro to Tensile Structures: References: Wolfgang Schueller, The Design of Building Structures Horst Berger, Light Structures – Structures of Light Hans – Joachim Schock, Soft Shells Maritz Vandenberg, Soft Canopies
  2. 2. Carnegie Mellon • Department of Architecture • Third Year Studio Definition: • Tension roofs or canopies are those in which every part of the structure is loaded only in tension, with no requirement to resist compression or bending forces. Vandenberg; page 6
  3. 3. Carnegie Mellon • Department of Architecture • Third Year Studio Classes of Tensile Structures • Membranes • The structural membrane acts also as the weathershield
  4. 4. Carnegie Mellon • Department of Architecture • Third Year Studio Classes of Tensile Structures • Cable Nets • A separate grid of structural cables supports a non–structural weathershield
  5. 5. Carnegie Mellon • Department of Architecture • Third Year Studio Classes of Tensile Structures • Pneumatics • The tension force is created by an interior positive pressure and the membrane acts as the weathershield
  6. 6. Carnegie Mellon • Department of Architecture • Third Year Studio Shapes • Anticlastic Surfaces • The centers of curvature of the membrane are on opposite sides of the membrane e.g. hyperbolic parabaloid, torus
  7. 7. Carnegie Mellon • Department of Architecture • Third Year Studio Shapes • Synclastic Surfaces • The centers of curvature of the membrane are on the same side of the membrane. E.g sphere or balloon
  8. 8. Carnegie Mellon • Department of Architecture • Third Year Studio A Simple Paraboloid • Defined by a Minimum of Four Points w/ at Least One out of Plane
  9. 9. Carnegie Mellon • Department of Architecture • Third Year Studio Equilibrium Forces • Anticlastic Surfaces • The surface is stabilised because the tension forces from prestressing or load are in equilibrium. • Synclastic Surfaces • The surface is stabilised because the tension forces from internal pressure are in equilibrium with the tension forces in the membrane.
  10. 10. Carnegie Mellon • Department of Architecture • Third Year Studio A Simple Example
  11. 11. Carnegie Mellon • Department of Architecture • Third Year Studio A Simple Example
  12. 12. Carnegie Mellon • Department of Architecture • Third Year Studio A Simple Example
  13. 13. Carnegie Mellon • Department of Architecture • Third Year Studio A Simple Example
  14. 14. Carnegie Mellon • Department of Architecture • Third Year Studio A Simple Example
  15. 15. Carnegie Mellon • Department of Architecture • Third Year Studio A Simple Example
  16. 16. Carnegie Mellon • Department of Architecture • Third Year Studio Deformations • By definition, the membrane can only resist forces in tension, so forces perpendicular to the membrane cause large deformations and large membrane forces. • Tensile roofs are susceptible to vibration. • Reverse curvature and/ or prestressing can bring these forces to zero.
  17. 17. Carnegie Mellon • Department of Architecture • Third Year Studio Materials • Uncoated fabrics • Simple woven fibers • Canvas, nylon • Coated fabrics • High strength woven fibers w/ coatings to prevent UV– & environmental degradation and improve weather resistance. • PVC–coated polyester: relatively short service life • PTFE–coated glass fiber: high strength, long service life • Foils • PVC– and ETFC– foil
  18. 18. Carnegie Mellon • Department of Architecture • Third Year Studio Edge Conditions • Rope Edge • A cable running in a sleeve and connected to a rigid structure at both ends • Hard Edge • A continuous connection to a rigid structure through clamping plates w/ or w/o prestressing devices.
  19. 19. Carnegie Mellon • Department of Architecture • Third Year Studio Point Supports • Masts capable of resisting compression and buckling forces. • The magnitude of forces at the point support require distribution via rings or umbrellas
  20. 20. Carnegie Mellon • Department of Architecture • Third Year Studio Line Shaped Supports • Arches – internal or External • Valley and Ridge Cables

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