A tower that speaks the language of efficiency and durability.

The Unipol Tower is one of the most significant additions to the evolving skyline of Milan’s Porta Nuova district. Construction began in 2018 and led to the development of a 125 metre high building comprising 23 above ground floors and 3 basement levels, with a total built area of 38,700 m². The project involved a total construction cost of €110 million, including €30 million dedicated to structural works.

The tower’s distinctive feature is its external steel diagrid, which forms the primary load bearing system together with two reinforced concrete cores located at the centre of the floor plan. Clad with timber elements, the diagrid creates a recognisable outer shell that evokes the idea of a protective envelope while fulfilling essential structural functions: it minimises the need for internal columns, enables efficient distribution of vertical and horizontal loads, and ensures greater flexibility in the configuration of the floor plates.

Floor systems alternate between primary floors connected directly to the diagrid nodes and intermediate floors suspended by steel hangers from the upper levels. This solution optimises load distribution and allows the building to maintain coherent structural performance despite its progressive tapering toward the top. The diagrid geometry and the key nodes—subjected to some of the most demanding stress conditions—were validated through advanced numerical modelling and dedicated non linear FEM analyses.

The presence of a high speed railway tunnel directly beneath the site required a highly controlled foundation strategy. Piles were positioned along the perimeter of the interference zone to avoid transferring vertical loads onto the tunnel, ensuring full compatibility between the building and the underlying infrastructure.

The tower’s aerodynamic behaviour was defined through wind tunnel testing on a 1:100 scale rigid model equipped with 256 pressure taps, followed by dynamic simulations considering more than thirty vibration modes. The experimental data were processed to derive Equivalent Static Wind Loads (ESWLs), which were used in the executive design stage to ensure reliable performance under wind loading. The building incorporates over 4,000 tonnes of structural steel in S355 and S460 grades for the diagrid, floor beams and hanging systems, contributing to a high performance structure that meets stringent sustainability requirements and has achieved LEED Platinum certification.