advanced building skins 14 | 15 June 2012 - lamp.tugraz.at - Graz ...

Advanced Building Skins
Façades as disconnected main structural elements embracing and protecting the inner building.
The disconnection allows (structurally) larger deformations making it possible to use formactive
lightweight façade structures that reshape under different load patterns.
After classifying the phenomena of flexibility, the first issue above will be described followed by two
projects with a disconnected form-active lightweight second skin façade.
2 Classification of Flexibility Phenomena
The total field of flexibility through deformation we divide in three main principles with in total six
typologies.
a) Principle 1: avoiding load impact.
This principle is about hiding, forming and smoothing. Three types can be mentioned:
reducing surface loading - changing shape to reduce the area of load impact,
reducing form factor - changing shape to become more aerodynamic,
reducing friction - changing skin texture to increase the smoothness.
b) Principle 2: improving efficiency of material
Materials and shape will react to its loading to improve their efficiency. The following types
belong to this principle.
activation of material - elements are activated by deforming,
configuration of material - changing the type and flow of internal forces.
c) Principle 3: spreading load impact in time
The energy of an impulse loading is spread over a certain time period so the maximum value
of the force on the structure decreases.
dynamic introduction of forces - spreading load impact over a period of time.
When we look at a three in a strong wind, the above given classification can be seen. Large
deformations to reduce the load impact (a), change in angle to decrease the bending and increase the
axial internal forces (b) and the dynamic behaviour under wind gusts (c).
Figure 1: Flexible behaviour of a tree under wind load.
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