afst.bundel 8 MEI 07 - Technische Universiteit Eindhoven

Afbeelding 2 Parameter Scheme: Filling - Skin
Afbeelding 3 Pre-stress Derivation: Direct and Indirect Component
afstudeerbundel faculteit bouwkunde
Afbeelding 5 Reconfigurable Formwork System
concentrating on the individual properties of the two main
components: the (enclosing) skin and the filling. The structural
as well as architectural qualities of vacuumatics are further
explored by means of several small scale models and prototypes,
as well as a material study of the filler elements.
The aim is to gain fundamental understanding in and control
over the underlying design principles so as to be able to
optimise structural assemblies to specific conditions and
required behaviours.
The behaviour of vacuumatic structures depends on the exact
nature of the materials used. Although almost any type of filler
material may be applied with vacuumatics, their enhanced
structural properties in vacuumatic state are essential, since this
determines the final capacity of the structure with regard to
strength, stiffness and stability (and therefore safety).
The vacuum pressure acting on the covering foils causes this
skin to be tightly wrapped around the surface of the filler
elements, hence resulting in a pre-stress of the vacuumatic
structure. The skin in particular seems to be of big importance
to the structural potential of vacuumatics, since it not only
ensures the structure’s integrity (as it provides the essential
air-tightness), its deformation also largely determines the
distribution of the pre-stress throughout the structure.
The skin deformation is mainly determined by the elasticity of
the skin material, and to some extend by the compression
(and thus shrinkage) of the filling. The pre-stress force acting on
each (granular) filler element is found to be divided into a direct
and an indirect component.
The ability to adjust and control the reconfigurability of the filler
elements (and thus the flexibility of the structure) by means of
varying vacuum pressure results in the so called “reversibility”
of the rigidifying process, enabling vacuumatic structures to be
shaped over and over again.
Afbeelding 6 “New” Shapes in Concrete
The original “flexible” behaviour of vacuumatics in un-deflated
(or “re-flated”) state opens up many possibilities with respect to
the relatively low-tech realisation of free-form designs. In order
to literally mould vacuumatic structures into a certain desired
shape, some sort of morphological tooling is required that forces
the filler elements into their “final” configuration.
This process might be somewhat similar to the formwork with
the production of concrete structures, but especially the ability
to locally adjust the geometry has great potential with respect to
its effectiveness and implementation into the current building
industry.
The hazard of damaging the enclosing skin and subsequently
jeopardising the structural integrity of vacuumatics remains
probably the biggest obstruction of introducing these structures
into the current building industry as independent, primary and
“permanent” load-bearing structures. On the other hand, this
temporality and the advantageous characteristics of vacuumatics
(the ability to be “free-formed”, to be adapted, to create a degree
of randomness and to be repeatedly stabilised) seem to provide
the “ideal” boundary conditions for a truly flexible, re-usable and
most importantly reconfigurable moulding technique for the
production of complex shapes and textures in concrete.
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