Rabobank Utrecht
| Client | Rabobank Utrecht |
| Completion time | 2005 – 2011 |
| Market | Commercial real estate |
| Team | |
| In collaboration with | Kraaijvanger |
| Location | Utrecht |
| Project scope | 56,000 m² bvo new construction and renovation of existing office, and approximately 720 parking spaces in a four-level underground garage of 16,000 m². |
| Expertises | |
Towers and plaza
Structurally, it was better to connect both towers along their entire height. In the new design, the main building consists of two slightly twisted round towers, each 105 meters high, joined by a glass skin. The towers are connected with continuous floors. Every four floors, the floor steps inward, creating a four-story-high atrium. Around the towers, a large hall has been built with various amenities, such as restaurants. ABT designed the structure, ensuring that this ‘Plaza’ remains column-free.
Pile-slab foundation
ABT investigated whether the 105-meter-high towers could be founded on steel. However, the settlements turned out to be significant: 10 centimeters. Therefore, the pile-slab foundation was conceived. The idea of giving the building a different type of foundation has significantly reduced construction costs.
Faster and cheaper
The project also included parking space, which was initially planned to be under the building. However, a study by ABT revealed that it was cheaper to make the garage deeper, thereby significantly reducing its size. As a result, the parking garage could be built next to the towers, and the construction of the towers could be separated from the parking garage. This saved a lot of time. The project now includes a single-level underground parking garage beneath the towers and the Plaza, and a four-level underground parking garage next to the building, with infrastructure above it to facilitate public transport.
Diaphragm walls
During the construction of the parking garage, diaphragm walls were used as vertical earth retention and foundation. Diaphragm walls are thick, reinforced concrete walls formed in the ground, consisting of segments (panels). A major advantage of diaphragm walls over sheet piles is the limited disturbance caused by noise and vibrations. The system is also very suitable for large retaining heights. This is particularly important in Utrecht, as they were excavated to 24 meters below NAP (Normaal Amsterdams Peil). The ground level is 2 meters above NAP.
Bubble deck floor
The parking garage was equipped with bubble deck floors: a self-supporting floor system that, despite its limited thickness, provides sufficient space for installations. The system supports in two directions and has the significant advantage of a weight reduction of up to 35%. This leads to a reduction in supporting elements, such as walls, columns, and the building’s foundation. At Rabobank, all bubble deck floors were power-troweled, making a screed unnecessary.
