Innovative and contemporary renovation

The Isola district of Milan is said to have recently undergone a major transformation, making it one of the most attractive areas of the city. Due to the prime location of De Castillia 23 and its excellent transport links, Gruppo Unipol decided to renovate the building and occupy it as their headquarters.

Client requirement
Unipol says that it wanted to create an ‘innovative and contemporary’ building in keeping with the area. The large-scale restoration work aimed to completely change the building’s aesthetic features, but also to improve its functionality, energy performance and the overall efficiency of the building’s management.

The architects, Progetto CMR, proposed an unusual glass prism facade design, aimed at reflecting sunlight in a constantly different way. This required a method of connecting the glass support brackets to the hollow tubular sections forming the facade.

Design solution
The structural engineer for the project decided to specify the flush fit Hollo-Bolt by Lindapter, an expansion bolt that requires access to only one side of a structural hollow section (SHS).

Hollo-Bolt was reportedly chosen as it offered significant benefits including fast installation, high strength capacity, a clean visual finish, and a range of independent technical accreditations, which include the CE mark and ETA to achieve a design compliant with Eurocode 3.

Installation
The main contractor, MAP Carpenteria, used a total of 6,800 size M8 Hollo-Bolts to connect the glass support brackets to the facade framework of two buildings.

Installation was quick and easy as each bolt is simply inserted into pre-drilled holes and tightened with a torque wrench. The brackets then securely held each glass panel in the required position to create the facade.

Result
The specification of Hollo-Bolts provided an approved connection design compliant with Eurocode 3 that met the structural engineers requirements.

Hollo-Bolts also provided a clean architectural appearance, due to the flush fit head type, and excellent corrosion protection thanks to the zinc plated finish.

Key benefits – Hollo-Bolts

  • Fast, cost saving installation from one side.
  • Suitable for square, rectangular and circular hollow sections.
  • High resistance to shear and tension.
  • Unique high clamping force design.