Pleated    Structures

Introduction to pleating

Pleating refers to the practice of folding a fabric into parallel strips - known as pleats.

Examples of pleated structures

Exteriors. Many more exterior views are available here.

Komatsu dome
Odate Jukai dome
Tropicana Field

Interiors. Many more interior views are available here.

Komatsu dome
Odate Jukai dome
Tropicana Field

Pleating

Pleated membrane structures are a common type of architectural construction - in Japan.

Pleating replaces the high points used in many tensile membrane structures with high lines.

The pattern provides regular structural support to the membrane, using cables.

Such a pattern typically involves parallel cables - with valley cables pushing the fabric downwards from above and ridge cables pushing it upwards from below.

The result is a surface which appears to be regularly folded.

In some ways, pleating is the tensile version of corrugation.

Advantages

There are many advantages to using a pleated pattern:

  • Strength and span: the limit of the tension in such a membrane surface is limited by the strength of the steel cables - rather than by the tension capacity of the membrane itself - allowing for much tauter fabrics than would otherwise be possible.

  • Low profile: near-horizontal surfaces can be employed. The membrane itself is not near horizontal, and the high tension cables are effective at preventing pooling - eliminating spots where rain water might otherwise collect.

  • Flat panels: the pattern lends itself well to flat, rectangular frameworks. These are commonly used in buildings - most walls, floors and roofs in the world consist of what are essentially flat panels, or composites of them.

  • Economical: the near flat surface saves material compared to use of a pattern with high points.

  • Proven: the pattern has demonstrated utility in the field - and scales up well. Many large pleated structures exist - including one of the largest clear-span structures in the world: the 209m diameter Tropicana Field.

  • No patterning: if using a slightly elastic material, structures can be built that use the elasticity of the material as the source of any anticlastic curved surfaces - as is done in polytunnels. This approach means that sewing or welding the fabric into complex shapes can be dispensed with - and a simple flat sheet can be employed.

  • Simple patterning: if use of a flat sheet is not possible, patterning using simple strips may be effective.
    Often the use of simple patterns - like these:

    Vertical strip pattern
     
    Horizontal strip pattern
    ...may be possible. Use of such simple strip patterns helps to eliminate offcuts, and simplifies stitching and welding.

  • Flexible: clyindrical and conical shapes are well suited to the approach.

  • Shingling: shingling works well with the pattern - reducing the need for water-tight welding.


    Shingles
  • Retractable roofing: use of pleating offers a number of opportunities for creating retractable roofs and reconfigurable surfaces.

Disadvantages

  • Stability: while pleated patterns with doubly-curved anticlastic surfaces are possible, pleating mainly represents an alternative approach to stabilising a fabric - supporting it regularly with high tension cables.
    However, unless some kind of curved surface is used for the membrane, its surface is likely to have a tendency to oscillate.
    While the pattern encourages the use of flat surfaces - to avoid complex anticlastic patterning issues - there are disadvantages to going too far in this direction - since completely flat surfaces are the ones most prone to vibration and rippling.

  • Cost: while the pattern is economical on fabric, it does use additional cables - and sometimes struts.
    The materials and detailing associated with these will have its costs.

  • Time: the pattern may have some of its overheads in areas which affect construction time on site - rather than being confined to the factory - if there are cases where the cable network can't easily be pre-constructed on the ground before being lifted into place.

  • Aesthetics: the pattern's lack of large anticlastic surfaces means that it lacks some of the aesthetic properties associated with most tensile architecture - and may not produce such a distinctive profile against the sky.
    On the other hand, it looks less like that well-known low- budget structure, the tent.

Other applications

Pleating has many familiar applications.

There's a page devoted to those on this site.


Other applications page - thumbnail


Tim Tyler | Contact | http://pleatedstructures.com/