Antwerp Port House: a sparkling diamond with ArcelorMittal steel overlooks the Port of Antwerp

Detailed information

Architectural design and project scope

A former fire station in the Port of Antwerp, this listed, Hanseatic-style brick building was to be included in the architectural concept for the Antwerp Port Authority’s new office building with the aim to unite its roughly 500 employees under one roof. The winner of the architectural competition, Zaha Hadid Architects, opted for a vertical building extension in the form of an elongated sculptural structure reminiscent of the hull of a sailing ship with an irregular glazed facade composed of triangular elements. These glass triangles, both transparent and opaque, are arranged at different angles to each other to create ever-changing reflections of the sky, water, and built environment. The extension sparkles over the port like a diamond in reference to the city’s significance in the diamond industry.  

The project included the complete and careful renovation and restoration of the protected replica of a medieval Hanseatic house, the construction of the building extension, and the implementation of a two-storey underground car park below the forecourt. Additionally, the existing building’s central courtyard was converted into an atrium covered by a glass roof that rests on an elegant grid of T-shaped steel sections. The new and existing buildings are connected via a central circulation core in the atrium and a concrete bridge that offers a panoramic view of the area.

The building extension: flexible, structurally independent, and highly prefabricated thanks to steel

The extension building measures around 111 m in length, is 24 m wide, and 21 m high. Structurally, it is completely independent from the existing building.

The four-storey extension is designed as a torsion-resistant steel frame and consists of a roof and floor structure with an intermediate truss and two angled, lateral, and partly sloping facade trusses. The lower floor is suspended from these three longitudinal structural members that are composed of HE-A/B/M (700 and 800 mm) sections and diagonal HD 400 columns. In order to combat the strong winds at heights of between 28 and 44 m, an additional bracing system consisting of four transversally placed stringers adds stiffness to the structure.  The steel structure was prefabricated in workshops and shipped to the construction site in just six parts by barges.

The building’s weight is supported in its entirety by a structure of concrete and steel: two concrete supports and steel columns are the main elements of the load bearing structure. The main support is prominently placed in front of the building in the form of a sloping, sculpture-like concrete column that is anchored deep in the foundations of the underground car park. The concrete circulation core and the inclined, black painted steel columns - providing lateral stability and arranged like an unfolded paperclip - are situated in the courtyard of the existing building and pierce through the new glass roof. The four black steel columns, measuring 46 m each, are made of 45 mm thick steel sheets and meet at the atrium floor to form the apex.

The supports are connected at the top by the concrete bridge and below the ground by a beam that runs between them, crossing under the southern wing of the existing building. In this way, a vertical ring of concrete is created.

An independent structure, made from steel and consisting of three vertical trusses, was built to house the four lifts that connect the existing building with the new building. It is entirely suspended from the second floor of the extension structure via two steel beams of HEM 650.

ArcelorMittal supplied 500 tonnes of HD columns in HISTAR® 355 steel for the steel structure of the building extension. HISTAR® is a high strength steel with low alloy content that can be easily welded, usually without preheating. Thanks to the application of the innovative in-line heat treatment QST (quenching and self-tempering), HISTAR® steels, unlike most standard grades, offer improved guaranteed values for yield strength throughout the entire product range. Considerable savings can be achieved during the welding stage, as well as with the cost and weight of steel structures making it an ideal material for sustainable construction.

Sustainability: BREEAM Very Good rating

Environmental criteria were key for the construction of the Port House. A construction site close to the water brought numerous benefits for sustainable construction as the materials and building components could be transported directly on the water. Despite the challenges that the integration of a protected historic building brought, high standards of energy efficiency were achieved at every stage of construction. In terms of building use, heating and cooling is achieved via a borehole energy system that pumps water to 80 m below the ground in more than 100 locations throughout the building. This system uses chilled beams in the existing building and chilled floors in the extension. In addition, waterless lavatory fittings and motion detectors keep water use to a minimum, while building automation and the optimal use of daylight minimise the need for artificial lighting.