Components and Details

Architectural Fabric Structures are the marriage of engineering and architecture and rely on the "engineer's aesthetic" to determine the size and shape of structural components.

The beauty of fabric architecture is in the few components required to create such a structure. These elements include the primary structure and specific components related to the structure, the fittings and hardware used to tension the membrane and the membrane itself.

Mast or Compression Members

Most fabric structures require a compression member (mast or arch) to form a complex shape.  The component usually has welded “cleats” or “struts” which enable it to support the membrane, cable or other structural components.

Base Plate

The base plate forms the connection between the tension membrane structure and the ground, wall, building or adjacent structural system. The base plate is usually welded to the bottom of a compression member or separated from the mast and connected to the mast with a pin connection.

Membrane Plate

Membrane plates are the most time consuming components to design and the key to successful tension membrane structures.  Membrane plates provide a “link” from the membrane to the structural masts. These plates are installed to accept membrane catenary cables and pin connection hardware.

Bale Rings

Bale Rings are compression rings which are used at the top of conical shaped structures that are used to erect and support the membrane at the top of a mast. The membrane is normally clamped to the ring and the entire structure is tensioned at the top by “lifting” the ring. Bale rings vary in shape and size depending on the complexity of the design. They can be left opened, covered by a metal, fabric or glass top, to name a few.

Catenary Cables

“Catenaries” are formed along the fabric perimeter stretching from mast to mast. Catenary cables are installed inside a pocket in the membrane or supported along the edge with cable straps and usually terminated with a threaded end stub or forked clevis that is connected to the membrane plates. 

Tie downs

Each perimeter mast requires either a large moment connection or a series of cable tie downs to withstand the loads. Tie down cables are generally attached to cleats on the top of a mast and connected to anchors installed in the ground with turnbuckles.

Specialized Hardware

Fabric Structure hardware consists mostly of parts made for yacht racing, bridge building, rigging and mountain climbing industries.  Shackles, turnbuckles, “toggles” and carabineers are just a few of the hardware choices available.  These components are the link between the membrane and the primary structural support.

Clamp Plates

Clamp plates are normally used to provide a watertight seal along a frame, beam or adjacent structure. The material most often used is aluminum or steel. The clamp can be extruded or cast to have a distinct profile.

THE DETAILS

One’s signature or style is often expressed in the details of a project.  Detailing fabric structures is no different.  Architects, designers, consulting engineers and clients all have different ideas on how a fabric structure and its details should look. The designer must take into account the different demands required for the details during the life of a fabric structure and subsequent cost.  Issues to consider are the following:

Economics

The cost of designing custom components needs to be weighed against the use of semi-finished products (i.e. tube, pipe, etc.) and fabricated parts (bolts, nuts, shackles, etc.). Selecting the method by which primary components are made can greatly influence the overall cost of a structure.  A minimum number of elements are usually desirable.

Material

The different material properties (strength, thickness, elasticity, weight, etc.) make material selection critical.  For example, use of high tensile materials with smaller cross sections most often implies higher material cost.  However, using low strength materials with larger cross sections increases the weight and cost of the installation.  A need for components to be highly abrasion-resistant, low maintenance and “vandal proof” also influences the choice of suitable materials. Some materials

Production

Various production processes (welding, forging, casting, etc.) have their own advantages and disadvantages that dictate the design of structural components.  In addition, the quantity of parts required (single vs. mass production), play a significant role in determining whether a custom component is feasible and cost effective.  Lastly, the ability to transport components to the job site must be considered.