Civil Engineering Reference
In-Depth Information
3.4.3 The Case Study: The New Juventus
Stadium in Turin
'
The round robin exercise is based on the repetition, in different laboratories, of a
commercial biaxial test commonly used by designers and manufacturers of ten-
sioned membrane structures. For this research a representative Italian project under
development during the research has been selected. The project is the membrane
roof for the New Juventus Stadium designed by Hernando Suarez (Studio Shesa)
and Gino Zavanella (Studio Gau), with the contribution of Francesco Ossola and
Massimo Majowiecki for the structural design. The membrane structure has been
developed by FormTL and realised by Canobbio S.p.A (Lombardi
2012
).
The roo
ng structure is supported by two A-shaped masts 90 m high, which
sustain, through steel cables, the hanging covering at its four corners. The shape has
been carefully studied from the aerodynamic point of view, obtaining a pro
le like
that of an aeroplane
s wings to avoid wind turbulence. The effects of wind on the
structure have been studied in the wind tunnel at the Politecnico di Milano and the
results have been used for the design of the membrane covering.
The surface is characterised by a low level of curvature which leads to diffi-
'
-
culties in the control of the de
ection under load, which is generally achieved
through higher levels of pre-tension in the membrane, with a consequent increase in
the sensitivity to changes in fabric stiffness. The effects of the curvature on the load
bearing capacity of a tension structure has been investigated by Bridgens and
Birchall (
2012
) who highlights the key role of the curvature in emphasising or
reducing the uncertainties on the material behaviour. In this context, the level of
uncertainly in the determination of the material
fl
s mechanical properties can result in
a higher risk of water ponding and snowdrifts. Therefore, the correct compensation
of the membrane and the level of pre-tension becomes a crucial factor for the safety
of the structure.
For this reason, FormTL, in charge of the design of the membrane roo
'
ng,
planned an accurate test campaign on the materials and the construction detail.
A considerable part of the testing carried out concerned the determination of the
biaxial behaviour of the PVC-coated polyester fabric. The object of the round robin
exercise here described is the analysis of the level of repeatability of the biaxial
loading pro
le developed by FormTL for the New Juventus Stadium
3.4.4 Methodology
3.4.4.1 Sampling and Preparation of Test Pieces
The material analysed is the PVC coated polyester fabric 1302 T2 produced by
Ferrari S.A. used by Canobbio S.p.A.in the realisation of the New Juventus Stadium
in Turin. All the samples tested belong to one of the batches of material. The
rst
sample of material, actually used in the project development, was tested at the
