THE ROLE OF FABRICS IN TENSAIRITY - Eawag-Empa Library

To strengthen the research of Tensairity structures is the main focus of the recently founded Center for
Synergetic Structures, a private public partnership between Empa and prospective concepts/Festo. For
this purpose, new test facilities will be set up at Empa to study the behavior of Tensairity structures.
These studies will help to deepen the understanding of Tensairity and to further optimize the
technology and its applications. A special focus will be set on the mechanical characterization of the
fabrics, as the fabric with its non-linear material behavior is a relevant part of Tensairity.
Important properties of Tensairity are shown in Figure 2. Each property is related to the underlying
airbeam or cable-strut structure, where it is inherited from. Little weight and small transport volume are
properties of both the pneumatic structure and the cable-strut structure. The capacity to carry heavy
loads goes back to the cable-strut structure, while fast set up, the temporary nature, thermal insulation,
lighting options, adaptiveness and so on do have their roots in the pneumatic structure. The low air
pressure is an emergent property of the combination of both structures and therefore shown with
dashed arrows.
pneumatic
structure
Tensairity ®
Tensairity ®
Tensairity ®
- light weight
- heavy loads
-low pressure (~100 mbar)
- small transport volume
- fast setup
-temporary
- thermal insulation
- transparency
- lighting
-floating
- adaptable
-safe
Figure 2. Properties of Tensairity, a synergetic combination of a pneumatic structure with a cable-strut
structure.
An important issue is the safety of Tensairity. The vulnerability of the airbeam is an undesired property
of Tensairity taken over by the pneumatic structure. An injury of the hull of a pneumatic structure leads
to a loss of air and the resulting drop of the air pressure endangers the integrity of the structure. The
situation is different in Tensairity due to an inherited property of the cable-strut structure. The struts or
chords in Tensairity have a resulting bending stiffness. They can be designed such that the dead load of
the structure is carried by the chords without the need of the stabilisation of the airbeam. The air
pressure is needed for sustaining the additional live loads [2]. In a lightweight Tensairity structure as
the roof over the parking garage in Montreux, the live load is roughly ten times higher than the dead
load. Stabilization by the over pressure is crucial for the live load, but the integrity of the structure is
not jeopardized with zero pressure solely under dead load. It also enables a pressure release in a
Tensairity structure when e.g. people have to enter the airbeam for service reasons. In structures like
the roof in Montreux high live load events are rare. The risk of a complete air loss in a Tensairity girder
with a high live load at the same time is very small. Furthermore, all larger Tensairity structures are
connected to an external fan, which starts blowing when the pressure drops below some threshold value.
This fan can easily compensate undesired air loss caused e.g. by a gun shot of vandals. And the
3
cable-strut
structure