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When forces converge within a tension structure, the connections between each of the three systems —fabric membrane, supporting structure and tensioned cables— are critical to a successful design.
The conditions of transferring loads from one of these systems to another can be grouped into edges, linear supports, point supports, corner supports, masts and base plates. The design of each condition has evolved over decades and decades of adapting details from different industries, such as sailing vessels, circus “big top” (chapiteau) tents, construction cranes and rope climbing rigging.
Edges
There are two types of edge conditions, flexible and rigid (or firm).
Flexible edge details tend to follow three designs:
- Fabric pocket with cable
- Edge cable with clamps
- Belts
Rigid edge details also follow three designs:
- Clamped edge with plates
- Channel (with grommets) and lacing
- Tube in cable pocket
Linear supports
Linear supports can include several forms, such as arches, ridge and valley cables and eye cables.
- Arch
- Ridge & valley cables
- Eye cables
Point supports
As with linear supports, point supports can take several forms including bale rings, “butterfly” forms and loops.
- Bale ring
- Butterfly
- Loop
Corner supports
Corner supports transfer loads from cables to structural columns and help transfer tangential forces downward to foundations. There are several types of corner supports, each involves corner plates.
Some types of corner plates:
- Corner plate apart from fabric (cables have separate adjustability)
- Corner plate clamped to fabric (cables are adjustable)
- Corner plate with keder/fabric edge (cables adjustable or fixed length)
- Corner plate with connecting belts
Masts
As their name implies, masts are tall, linear structural elements (usually of steel) resembling the masts of sailing ships and are used to hold up the fabric membrane and cable elements of a fabric structure. These are the most directly visible expressions of the tremendous compression forces that develop within tension structures and carry these forces to the ground. To compensate for any twisting or natural torsion that may develop, masts are frequently fastened to the foundations with hinged base plates.
Base plates
Base plates are further divided into plates for masts and for cables, each with three subcategories:
Mast base plates
- Moment resisting
- Single hinge
- Ball & socket
Cable base plates
- Moment resisting
- Single hinge
- Double hinge (w/extra toggle)