Innovative steel structure for the Area 22 mixed-use building

Detailed information

The idea was to create a multipurpose environment proposing a modern concept of space for commercial and other uses. To meet the typical requirements of businesses, shops, showrooms, offices, warehouses, depots, garages, car parks, road traffic, and visibility, additional services were added such as restaurants, bars, newspaper & tobacco stands, banks, conference rooms, executive offices, reception, and entertainment spaces. The presence of a 4-star conference hotel also makes the whole environment very pleasant and well-kept, thus offering ideal conditions for locating one’s own business or opening a new one.

Although developed in a single volume, the project incorporates three different environments (commercial, office management, reception) which, precisely because of their apparent heterogeneity, will contribute to stimulating interesting synergies and interrelationships to the benefit of all those involved.

The intervention consists of at least two volumetrically distinct parts: the commercial and services area, which was developed over three levels to cover a height of up to 15 m, and the prismatic building of the hotel, which, being located in the southern part of the tapered lot, rises to a height of 9 floors to reach 30 m.

The buildings of the project are extremely visible in all conditions: from the motorway, from the national road, and from the railway, the complex can be fully perceived with a glance, within a few seconds. Project designer, architect Mr Ferreguti, recalls that the constructed volumes are confronted with a visual fruition, extremely fast and 'lateral' in which the masses, the colours, and the rapid perspective variations dominate. A new landmark in the valley, the construction is made attractive and mysterious by the unexpected distortions of the faces of the prismatic volume of the hotel rising from the surrounding texture, cutting through the landscape as a bastion built to protect the renaissance town: caught between the railway and the motorway, it appears to be dynamically deformed by the powerful lines of force that streak the landscape longitudinally.

Because of its complexity and the joint coexistence of such different activities, the project was also subjected to Environmental Impact Assessment screening by the province of Trento in addition to the necessary countryside protection studies by the Territorial Authorities, obtaining all necessary preliminary permissions.

The use of steel

Steel is a material that offers many advantages in construction and architecture: great compositional freedom, lightness, mechanical resistance, durability, and being 100% recyclable in respect for the environment. It also offers low cost and speed of execution: steel structures are prefabricated in the factory and transported to a site 'just-in-time.' For Area 22, Premetal Company, a leader in the metal construction sector, was able to guarantee a high technical level in the management of the entire process, from the working drawings of the design to implementation of the components in the workshop, assembling on site, and the completion of the construction.

While realising the commercial structure of Area 22 in three levels above ground, a steel-concrete construction was used comprised of conventional and more innovative types of beams integrated in the slab, IFB (Integrated Floor Beams), and a construction technology that combines and leverages the best of the properties of both materials. The building framework (beams and columns) is made of steel, while the floors are designed with pre-stressed concrete hollow core slabs resting on the wings of the metal girders. The transverse reinforcement inside the completion concrete casting of the floor slabs and welded rungs on the upper wing of the metal girder ensure strong bonding between steel and concrete, giving rigidity to the structure. The columns of the basement are also of the mixed-system type, made up of a hot rolled steel section caged by non-prestressed reinforcement and finished with a layer of concrete.

The technology of steel-concrete construction offers many advantages: increased resistance and stiffness to the sections and therefore reduction in the deflection of the beams allowing for the bearing of high loads without compromising on the spans of the floor slabs (which in the case of Area 22 reach 15 m) and the dimensions, through the use of beams integrated in the slab, IFB (24 to 50 cm, with honeycomb pre-compressed slab). This system involves a significant reduction in time and site impact, allowing quality control, typical of prefabricated structures. In addition, the fire resistance requirements are easily met, since the steel surfaces exposed to fire are very small.

An important characteristic of the Area 22 project is the use of two innovative steel solutions for Italy: columns made of S460 rolled steel beam with high thermal-strength and beams integrated in the slab - IFB (Integrated Floor Beams).

In particular, the choice of S460 high strength steel columns, generally used in buildings with large height, was imposed due to the need to reduce the column dimensions and the weight of the structure. In fact, for an equal load, S460 high strength steel columns allow a lower section compared to conventional steel columns, which is why the extra cost of the quality of S460 is offset by a significant reduction in the steel used.