Mahmoud Ibrahim, Project Manager, Construction Claims SpecialistLocated on a prominent site in Kuwait City, the 300-meter-high, 60-floor tower, headquarters of the National Bank of Kuwait (NBK) is set to have a distinctive presence amongst other high-rise buildings in Sharq – a growing financial district. The design combines structural innovation with a highly efficient passive form, shielding the offices from the extremes of Kuwait’s climate where temperatures average 40 degrees in the summer months. SSH acted as lead consultant for construction supervision in association with Foster + Partners and BuroHappold.
Pearl shell-inspired design
The tower’s cylindrical form opens like a shell to the north to avoid solar gain, while revealing views of the Arabian Gulf. The southern façade is shaded by a series of concrete fins, which extend the full height of the tower to provide structural support. As well as contributing to the environmental strategy, these ribs help to evoke a sense of place in echoing the form of the dhow sailing boat – a reference to the city’s roots in international trade. By tapering towards the base, the design maximizes floor space in the upper levels and promotes self-shading, as the overhanging floor plates shelter the offices below.
Utilizing both passive and active measures to reduce water and energy consumption, the project targets a LEED Gold rating. The main construction comprises composite concrete and steel, while the cladding on the fins and glass façades is predominantly glass reinforced concrete.
The form of the tower is equally driven by the needs of the Bank. The spatial arrangement is tailored to the Bank’s organizational structure, while providing the flexibility to anticipate and respond to future change and growth. The crescent form maximizes cellular office space at the perimeter, and the tower’s 60 floors are punctuated by three double-height sky lobbies, which provide a social focus and meeting facilities for staff. These communal areas are complemented by the Chairman’s Club with panoramic views in the dramatic 18-meter-high volume at the tower’s apex.
Based on its energy-saving and environment preservation designs, NBK Tower is a new landmark green building built in line with LEED (Leadership in Energy and Environmental Design) Gold requirements, making it one of the first with such high certification in Kuwait and the region.
Challenges and Technological Solutions
The fact that the NBK tower is located in the heart of the capital, made it a significant challenge due to the strict restrictions by the municipality on the travelling and movement of heavy machineries, truck and trailers. The timing of incoming deliveries had to be carefully planned, to be allowed to enter the capital area. And like any other project, safety is a major concern, but this was magnified even further due to the unique shape of the tower, and its location in a 24-hour busy district with a highly congested population in the nearby towers.
The main challenges that shaped and directed the project’s critical path can be summarized in 5 points:
The unique shape and façade of the tower, particularly the top of the building: Inspired by the shape and lines of pearl shells, the tower façade installation was extremely complicated. Originally, only two main luffing lib tower cranes were penetrating through the tower and were used to install majority of the structural elements, in addition to a fair percentage of the façade glazing and glass reinforced concrete (GRC) panels at the tower fins. These cranes were eventually replaced by three relatively small derrick cranes fixed at the top of the arch tower to cover the entire façade. The temporary supporting system for these three derrick cranes was an immensely complex 80 tons of steel profiles, which had to be removed piece by piece towards the end of the project.
The GRC cladding panels are supported by 4 to 10 brackets, welded to the main skeleton, and each with its unique set of coordinates, which had to be implemented with high precision. Between fabrications, delivery, setting the bracket coordinates, welding, and finally fixing the GRC panels, this activity alone consumed millions of man-hours.
But one of the most exciting scopes was the top of the tower (known on site as the crown) - an extremely curved, stick system glazing made of 199 glass panels, fixed with an accuracy less than 1 mm at the extra ordinary height of 300 meters. With careful planning, the entire system, starting from the on-site welded mullions and which transoms down the last glazing accessory, was fixed within 3 months.
The world largest building maintenance unit BMU: The new NBK headquarters holds the record for the largest BMU ever installed. Taking a space of two floors and located about 250 meters above sea level, lifting each part of the BMU down the testing and commissioning of this engineering breakthrough, was very laborious and tricky.
The twin elevator system: The project is distinguished by the ‘twin elevator system’ (used for the first time in Kuwait). Inside each of the 10 reinforced concrete shafts is a set of twin elevator cabins, each moving independently, and reaching a staggering speed of 6 meters per second.
High quality finishes: With the majority of finishes made out of natural elements, such as the Luminoso wood, Quartz tiles, Nero Perla tiles, the delivery and installation went under a strict quality process in order to achieve the current impressive final product.
Removal of derrick cranes & use of BMUs: Towards the end of the project, all three remaining derrick cranes were dismantled, with the exceptional task of dismembering 80 tons of temporary supports, all using the world’s largest BMU.