"Steel Feeds Innovation" is the theme chosen by Fondazione Promozione Acciaio which brought together 19 business realities of the sector to finally put the steel construction in the middle of an important and relational exhibition like MADE expo. The dissemination activities of the culture of steel in architecture, which for years characterized Fondazione Promozione Acciaio, takes a step forward, bringing together for the first time in a single exhibition space some of the leading members of the construction industry in steel: from production to building phases. Fondazione Promozione Acciaio presented significant projects for Expo Milano 2015, for which it was crucial the choice of steel: some pavilions (Argentina, Bielorussia, Brazil, United Arab Emirates, Germany, Japan, Israel, New Holland, Holy See, Thailand, Czech Republic), Sail Cover of Palazzo Italia, Expo Gate, Tcp, Expo Gate, Cardo and Decumano Awnings, Open Air Theatre and Footbridge Expo - Cascina Merlata.

In particular, the footbridge Expo - Cascina Merlata (PEM) fits into a context of important transformations in occasion of Expo 2015 and it represents an element of the conjunction of two projects: the exhibition area and the intervention of Cascina Merlata, a little further south. Key feature is its permanent nature.
Several dimensional constraints have influenced the morphology of this pedestrian walkway: crossing over the railway line and imposed safety distances both by the same railway line and both from the toll road, with the aggravating circumstance of having to place the piers in an area full of underlying utilities. This has led to design a work fully developed in elevation, 6 m wide with a height varying from a maximum of 9 to a minimum of 4.4 meters. The footbridge is constituted by two statically indeterminate sections with spans of 65 and 80 meters (Expo side) and with spans of 50, 105 and 41 meters (Cascina Merlata side) for a considerable overall length of 341 m, partly in level (about 180 m from the extremity south) and the remaining part in slope (5%).

Daniele Mascolo - Expo 2015 (3)[1]
© Daniele Mascolo
Particular attention was paid to the “human comfort” or the perception of the vibrations produced by wind and transit of pedestrians. The preliminary design to ensure the comfort of the user included the performance of steel piers with the possible adoption of damping devices in order to limit the vibrations. During the working plan, the comfort has been prosecuted following other methods, eliminating the use of damping devices and replacing unfortunately the elegant steel piers with other more robust and cumbersome concrete ones.
The PEM is a lower girder bridge, formed by two wall steel lattice beams arranged vertically along the longitudinal development of the walkway, closed both at the upper and lower level by a ceiling realized by a double beam steel layout and stiffened by a bracing system.  IPE and HE profiles, square and rectangular hollow sections, box girders for a total of 1.200 tons of steel grade S355J0 conform the structure of the walkway. Steel is also present with the corrugated sheets of the decks and in the particular drilled sheets of cladding.
The project of the Open Air Theatre is about a space of 51 meters of light totally free: the coverage in the spatial network is made by tubular S355JR; they have been installed, also, self-supporting sandwich panels with finish in sheet steel, prepainted for the opaque part.

© Studio Mondello
© Studio Mondello


Client: EXPO 2015 spa
Preliminary project: Ufficio di piano Expo 2015 spa Dir. Construction & S. M.
Chief architect: Ciro Mariani
Structures: Monica Antinori
Executive project: Metropolitana Milanese spa
Structures: Roberto Conta
With the collaboration of: Stefano Rossi
Companies: Giugliano Costruzioni Metalliche spa, R.C.M. Costruzioni srl
Pictures: Ufficio di Piano di Expo (preliminary design), Giugliano Costruzioni Metalliche srl, Metropolitana Milanese (executive design), EXPO 2015 – Daniele Mascolo (pictures)

Preliminary project: Ufficio di Piano Expo 2015 spa Dir. Construction & D.
Chief architect: Ciro Mariani
Structures: Monica Antinori
Executive project: Metropolitana Milanese spa
Chief architect: Roberto Tornelli
With the collaboration of: Studio Valle Architetti Associati e MSC associati Srl.
General Contractor: Ing. E. Mantovani S.p.A
Pictures: EXPO2015 - Daniele Mascolo