Existing office building – Piazza San Fedele – Milano (MI) – Italy

Refurbishment with seismic retrofitting; preliminary, final and detailed design of structural works

 

Client: BNP Paribas Re Property Development Italia S.p.A.
Buildings surface: 14.700 m2
Buildings volume: 56.000 m3
Structural works value: 700.000,00 €
Design period: 2007÷2010

 

The building has eight floors above ground and two underground floors with a structure entirely made of reinforced concrete cast in place and ribbed floor slabs lightened with hollow blocks, and is characterized by a large area of an annular shape supported by sixteen columns carried by a circular beam of height 1.50 m placed on the first mezzanine; the foundations are reinforced concrete footings.
The project involved the construction of four new decks in the internal circular area between the 1st floor and the 4th floor for office use.
Before to the design of the building modifications described, a complete survey campaign was carried out which, together with the documentation of the original project, provided an in-depth knowledge of the structures allowing to perform the structural assessment in both static and seismic conditions.
The new circular decks have a steel radial structure and have been connected to eight existing external columns as well as to eight new internal columns, replacing the existing sixteen demolished columns.
The retrofitting of the existing structure to the seismic actions envisaged for a new construction took place by strengthening of the existing reinforced concrete walls that have been enlarged with the addition of steel reinforcement, while the shear strengthening was done by gluing of carbon fiber fabric.
Also some of the existing footings have been reinforced, to make up for the existing lack of reinforcement, by adding to the extrados of reinforced concrete ribs.