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

Advanced Building Skins
For the frame, the limits "soft" and "rigid" were investigated. Here "soft" means free glass edges (x, yand
z-direction), "rigid" means simply supported edges of both glass panes in z-direction.
The interlayer is modelled with a Young's modulus of 1.0 N/mm² and a Poisson's ratio of ν = 0.499.
The temperature difference T was increased progressively up to 20°C (e.g. rain cooling). Figure 8
shows the stress distribution of the finite-element calculations which takes into account geometrical
nonlinearity.
Figure 8: Principle tensile stresses on the outer surface of the upper glass pane with symmetrical (left) and
asymmetrical (right) temperature distribution and soft frame
The maximum principal tensile stresses occur under symmetrical load ΔT,1 at the outer surfaces. With
the asymmetrical load T,2 these are located on the outer surface of the upper glass pane (Figure 9).
Figure 9: Thermal expansion (ɛtherm) and tensile stresses (σmax) for symmetrical (left) and asymmetrical (right)
temperature distribution
Figure 10 shows an almost linear relation between temperature difference and the glass stresses. The
small differences arise from the geometrically nonlinear analysis. Furthermore, it indicates that the
consideration of the load case temperature can be quite relevant for structural design, especially if the
capacity of the modules is already reached with other loads.
- 9 -