The base of the tower, made entirely of concrete, has a foundation varying from 2.5 to 3.5 m in height, connected to 52 drilled poles 1.5 m in diameter and 31.5 m long raising the eight glass and steel sails covering the 43 floors of the skyscraper, with its frame of steel reinforced with concrete.
The static scheme consists of a heart containing the primary services in the centre of the layout, separating the space on each level, characterised by five pillars per side with a circular base measuring 1.5 m in diameter, buried in each of which is a steel HE. On either side of the tower are other services necessary for the life of the building, such as staircases and new generation pressurised lifts which use a special software to direct employees to their floors as soon as they pass through the turnstiles at the entrance to the building. It is surprising to learn that the thickness of the walls of these two long bodies on either side of the tower does not exceed 50cm, keeping them both slender and rigid.
In view of the large front surface, during the design process a simulation was conducted with a 3D model in a wind tunnel to see how the building would oscillate and quantify oscillation appropriately in combination with the results of the mathematical and structural model. The final calculation and laboratory results made it possible to conceive and build a structure in which oscillation at the top of the tower does not exceed 80cm. All this thanks to four struts that add further rigidity to the already solid steel and concrete frame. Because of the weight of these exposed structures, to prevent excessive camber due to the redundancy caused by wind, they have been emptied out, dividing them in three while leaving them joined by big steel plates, also lightened to prevent the inconvenient sail effect from having repercussions on the tower. One final detail is the connection to the ground visible on the entrance level on one side, while on the other side the hinge rests on the roof of two large utility volumes at the back of the tower.
Design: Allianz Tower Milan programme skyscraper for client’s offices Citylife S.p.A. / Armando Borghi - CEO, Marco Beccati
Construction: 2012 - 2015
Design: Arata Isozaki and Andrea Maffei
Final advanced project design team: Pietro Bertozzi, Takeshi Miura, Alessandra De Stefani, Chiara Zandri, Davide Cazzaniga, Vincenzo Carapellese, Roberto Balduzzi, Takatoshi Oki, Stefano Bergagna, Paolo Evolvi, Elisabetta Borgiotti, Adolfo Berardozzi, Higaki Seisuke, Carlotta Maranesi, Francesca Chezzi, Giuliano Godoli, Giorgio Ramponi, Hidenari Arai, Takuichiro Yamamoto, Atsuko Suzuki, Sofia Bedynski, Antonietta Bavaro, Mauro Mazzali, Sofia Cattinari, Taro Hayashi, Haruna Watanabe, Madoka Tomita, Ayako Fujisawa
Competition structures: Mutsuro Sasaki, Hiroki Kume, Takeshi Suzuki / Sasaki and Partners, Tokyo;
Design structures: Maurizio Teora, Luca Buzzoni, David Scott, Matteo Baffetti, Valeria Migliori, Francesco Petrella, Angelo Mussi / Arup, Milan and New York,
Plate structures: Holzner Bertagnolli, Cap Engineering
Facades: Mikkel Kragh, Mauricio Cardenas, Matteo Orlandi, Maria Meizoso, Carlos Prada / Arup Milano e Madrid
Competition installations: P.T. Morimura, Tokyo
Design installations: Gianfranco Ariatta, Roberto Menghini, Riccardo Lucchese, Sylvia Zoppo Vigna, Andrea Ambrosi / Ariatta Ingegneria dei sistemi, Milan
Artistic direction: Andrea Maffei / Andrea Maffei Architects
Photos: Alessandra Chemollo