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Tensile and fabric structure design

Design of tensile fabric and membrane structures, tensile shades and cable structures: the membrane, the steel masts and arches, the cables and the anchorages.

Tensile fabric structure: a long white membrane roof on curved steel arches over a building entrance, lit at dusk

Wrenze Steel designs tensile fabric structures, membrane roofs, tensile shades and cable structures for contractors, fabricators, architects and developers in Dubai, across the UAE and in the GCC. A tensile structure works with the membrane and the cables in tension and the steel in compression and bending, so the fabric, the cables and the steel have to be designed together, from the form finding to the anchorages.

Tensile structures we design

  • Tensile membrane roofs: PTFE and PVC fabric roofs over entrances, courtyards, stadium stands and walkways
  • Tensile shades and shade structures: tensile shade sails, canopies and outdoor shading for schools, parks and public spaces
  • Tensile car parking shades: single and multi-bay car parking shade structures with HDPE or PVC fabric
  • Cable structures: cable-stayed footbridges, cable nets, cable-braced roofs and their anchorages
  • ETFE roofs: transparent cushion and single-layer roofs on steel frames
  • The supporting steel: masts, arches, ring beams, frames and foundations for every type above

What tensile structure design covers

  • Form finding. The membrane shape that balances the pretension, with enough curvature to resist wind and avoid ponding.
  • Membrane and cable analysis. Non-linear analysis of the fabric and cables under pretension, wind uplift and downward pressure, and other loads.
  • Steel design. Masts, arches, frames and compression members designed for the large forces the pretensioned fabric and cables apply.
  • Connections and edges. Edge cables, clamping plates, corner plates and mast heads, detailed so the forces pass cleanly into the steel.
  • Anchorages and foundations. Cable and mast anchorages into concrete, often in tension and at an angle, and the base plates and foundations below them.

Membrane materials

  • PTFE-coated glass fibre: long life and self-cleaning, for permanent roofs
  • PVC-coated polyester with a PVDF topcoat: flexible and economical, for canopies and shades
  • HDPE shade cloth: breathable shading for car parks and outdoor areas
  • ETFE foil: light and transparent, for skylights and atrium roofs

Codes and standards

We design to the project specification, typically with ASCE/SEI 55 for tensile membrane structures, ASCE/SEI 19 or EN 1993-1-11 for cables, and AISC 360 or Eurocode 3 for the supporting steel, with wind loads for the site. The membrane, cables and steel are analysed together in one non-linear model, so the forces used in the steel design come from the real tensioned shape.

Tensile and cable projects

On the Mushrif Park cable-stayed bridge in Dubai, Wrenze Steel provided full consultancy for Dubai Municipality: a curved steel deck carried by stay cables from a single inclined mast. At Expo 2020, we designed the cable anchorage connections for the Brazil Pavilion, where steel base plates carry the cable fittings into concrete plinths. We have also designed fabric canopies and shade structures in Al Ain, including the analysis of the fabric under load.

Tensile structures connect to several of our services: structural steel design for the masts, arches and frames, steel connection design for mast heads, base plates and cable anchorages, and shop drawings and detailing for fabrication. For car parking shades and solar car parks, see our canopies and solar sector.

Contact our engineers

For tensile fabric structure and cable structure design, contact our engineers.

Tensile & fabric structures: questions

What is a tensile structure?

A tensile structure carries its loads through members in tension: a fabric membrane, cables, or both, held in shape by steel masts, arches or frames. Because the membrane works only in tension, its shape is found by form finding rather than chosen freely, and the supporting steel is designed for the large forces the pretensioned fabric puts into it.

Which membrane materials do you design with?

PTFE-coated glass fibre for long-life roofs, PVC-coated polyester (often with a PVDF topcoat) for canopies and shades, HDPE shade cloth for car parking shades and outdoor shading, and ETFE for transparent roofs. The choice changes the strength, the pretension and the details at the edges and fixings.

What does tensile structure design cover?

Form finding of the membrane shape, analysis of the fabric and cables under pretension, wind and other loads, design of the steel masts, arches, frames and cables, the connections and edge details, and the foundations or anchorages that take the cable and mast forces into the ground or the building.

Do you design tensile car parking shades?

Yes. Tensile car parking shades are light structures where wind governs: uplift on the fabric, sway of the columns and the forces at the base plates and foundations. We design the steel frame, the fabric loads and the anchorage for single and multi-bay shades.

Do you design cable structures?

Yes. We design cable-supported structures such as cable-stayed footbridges, cable nets and cable-braced roofs, including the cable anchorages. On the Mushrif Park cable-stayed bridge in Dubai we provided full consultancy, and at Expo 2020 we designed the cable anchorage connections for the Brazil Pavilion.