Z E M C H 2 0 1 2 I n t e r n a t i o n a l C o n f e r e n c e
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It is important to specify that this structure and all other metallic structures in the light
wells have been designed with regard to deformability which here are of particular
interest since the structure that is supported is made up of sheets of structural glass.
Analyzing the above details one can notice the presence of a protection for the existing
walkway.
The gallery is located at a height of +16.50m. The protective structure is formed of
elements made of metallic grids called "Orsogrill", located beneath the balcony to fully
support the stone and the live load (about 6.80 kN/m2).
These panels are supported continuously on one side by the masonry and on the other
side by a rectangular steel tube (150x80x8 mm). An identical tubular steel element is
used at the top of the shelf to support the glazed facade and a section of the new
walkway.
In view of the structural calculation, it may be noted that the worst case is realized for
the outer steel tube (uniform load q
≅
9.80 kN / m, distance 3 m). The tube is a single
element, totally continuous (butt fusion, even for aesthetic requirements).
The deformability is therefore of 1.1 mm, in any case less than required by current
regulations.
Construction
Carrying out the project led to special issues related to the central historical context in
which the building is located especially as regards the supply of materials, such as
beams of considerable length, or bulky materials.Beginning from the foundations, these
are strengthened with concrete slab connected to the existing foundations through
crossing metal bars. These bars are fixed to the masonry with epoxy resin (figg. 25 &26)
Figure 25 : Foundation slab
Figure 26 : Foundation slab
Construction continued with the assembly of scaffolding necessary for the subsequent
construction of the new floors.
In view of the problems related to buildings in a historic context, the assembly phase of
the new metallic floors could not be conducted as usual, laying them in the correct
position in one single step, but it was necessary to put together every single beam of the
new floor directly on to the courtyard at the existing floor level.
This procedure was performed to preserve the building, forcing the designers to
undertake a very fine control of the operations as well as the installation procedures.
Every single beam is carried to the correct level using special cranes and then inserted
in the wall and secured with non-shrink grout (Emaco). After the laying of the main
beams we proceeded with the laying of the secondary beams connected to the main
beam with bolts and nuts (figg. 27 &28).
