Circle in the Sand

It had to be glass for the newly constructed HQ Building in Abu Dhabi. Concrete just wouldn‘t do. Located along Al Raha Beach, an 11 km long urban development region, the HQ Building is the first circular building to be constructed in the United Arab Emirates. Designed by MZ & Partners, the unconventional shape of the building, with two circular, bulbous, curved glass facades, offers open office and commercial space with flexible partitioning over 23 floors.

With a diameter of 120.9 meters and a depth of 36.4 meters in the middle and 10 meters at the edge, the HQ Building covers a total gross floor area of 61,900 square meters, comprising units of various sizes with diverse potential uses, depending. One part of the building is being used as the headquarters of Aldar, Abu Dhabi’s largest property developer while the remaining spaces will be leased. The building was developed in accordance with the LEED requirements of the U.S. Green Building Council.

MZ & Partners design, which had received the “Best Futuristic Design” award in 2008 at the Building Exchange Conference in Valencia, was made reality by engineering firm Arup. During this stage the team realized concrete was not an option as a construction material, as the structure has a 25 meter cantilevered design in every longitudinal direction. In addition to time-consuming and costly on-site construction work, a concrete structure would have required unwanted internal supports. With this in mind, the team developed a complex, grid-like, diamond-shaped steel structure, called a diagrid, simultaneously creating the building’s succinct façade look.

The diagrid comprises triangular elements that are linked via prefabricated node points. Various angles create the façade‘s three-dimensional cantilevered appearance. In this context, a rhomboid area extends over eight stories. This design construction transfers the majority of the resultant loads to the external skin and provides for an almost entirely support-free interior, with maximum flexibility for the floor plan and unhindered views. Two internal concrete cores that house elevators, emergency stairs and first aid rooms, are used to reinforce the construction.

The all-round, curved shape of the building creates additional, powerful horizontal forces in the floor ceilings under the weight of the construction itself. This is why the two circular facades are linked together via tie rods and a horizontal support connects the external, middle and internal supports for all floors.

The diagrid steel structure was sealed using more than 10,000 glass elements, supplied by Glas Trosch based in Switzerland. which had previously been assembled during the prefabrication phase to create approximately 9 square meter large, triangular panels with aluminum frames. The retaining brackets for the frame profiles determined the angle of each glass panel in the three-dimensional, curved structure.

The region‘s extreme climate conditions meant solar control for the 16,000 square façade was critical. As a result, the project features blue tinted with a SILVERSTAR SUNSTOP Blue 30 T coating, which provides an overall energy transmittance of 18 percent. The internal lite, made from clear glass, has a SILVERSTAR ENplus T coating.

“The very challenging color specification of our customer [was] achieved by using Glacier blue tinted glass combined with our bluish SILVERSTAR SUNSTOP Blue 30 T,” Fabrice Nussbaumer, marketing manager Glas Trösch Silverstar, told the Architects’ Guide to Glass & Metal magazine. “The result is a perfect harmony between the turquoise colored sea and the reflection in the glass of the HQ.”

Seamless logistics and a timely, efficient handling and construction process were fundamental, as the glass was transported by truck and ship container from Switzerland to Abu Dhabi. Once on site, White Aluminium Enterprises there performed additional fabrication steps.

The project team was spread throughout the world, with partners in Dubai, Sydney, the UK and Italy, so communication was very important. In order to ensure efficient teamwork, Building Information Modeling was employed during the initial phases. This gave all those involved parallel access to continually updated model data with the same degree of precision. This avoided interface problems in the planning and speeded up the manufacture of components and material procurement. Compared to conventional workflows this meant an approximate 25 percent reduction in the time required for the entire planning and construction process. The approach also allowed for overlaps between the timing of the planning and construction phase, enabling the facades to be sealed and the commencement of work on the interior fitting out in parallel with the construction of the internal floor structure and the steel support structure. The HQ Building was ready for occupation at the end of 2010.