Complex building in Amsterdam

Aronsohn consulting engineers – Netherlands

Building use

Office building

Country/Region

Netherlands

Overview

The building is a speculative investment that serves with offices and residences. The Main part is the office building that sits on the curve of one of the main canals in Amsterdam and it is occupied by the headquarters of Booking.com a large on-line travel agency with over 5000 employees. The building is designed with a very complex shape, with the top part elevated from the ground by sculpturally-designed columns. A 25 meter cantilever overlooking the parking entrance is another technical challenge of the building. Many composite elements are present in the building, two are presented here.

Basic information (construction date, number of stories, gross floor area, adopted design code, engineer(s), Contractor(s), etc.)

Construction date: 2019-2022
Number of stories: 6 in the office portion and 11 in the residential part
Gross floor area: 72,500m2 and 27,000m2 of underground car and bike parking
Adopted design code: Eurocode
Engineer(s): Pieters Aronsohn consulting engineers
Contractor(s): Ed. Züblin AG, Stuttgart

Issue and/or innovation

Floor system: the structural engineering company initially designed the floor as a 320mm thick prefab cassette concrete floor but the contractor proposed a variation with a composite floor system to avoid the delivery uncertainties of the cassette floor system to shorten the construction time. When incorporating the proposed change, the construction height of 320 mm in the original design turned out to be a compelling factor.
W-columns: The W-shaped columns present an unique shape and very large dimensions and extremely heavy weights.

Reason for composite solution

Floor system: The composite system was chosen over the previously-considered prefab concrete cassette floor to avoid delays in the delivery of the cassette floor, and shorten the construction times of the project.
W-shaped columns: Composite was the most viable way to create such large columns are provide them with an inherent fire resistance.

Specific solution/technical details

Floor System: above lever 4 the floor system uses a composite system of steel and metal decking with a 300mm thickness over a span of 8.4 meters. The metal decking has a thickness of 1mm with 210 mm of ribs and a compression layer of concrete of 90mm. The metal deck lies on the bottom of the steel beam. In the prefab floor of 320 mm thickness, a recess was provided during installation so that the bottom of the floor and the bottom of the beam correspond with each other. With the steel plate-concrete floor, the floor thickness could be reduced to 300 mm, but with the original bottom flange thickness of 35 mm, the construction height would increase to 335 mm. In order to obtain the required moment capacity and stiffness. To maintain the bottom flange cross-section, it was decided to use a double one bottom flange: the bottom one that supports the steel-plate-concrete floor has a thickness of 20 mm, so that the maximum construction height requirement is now met. The top bottom flange provides the remaining contribution to strength and stiffness.
W-shaped columns: The W columns with a length varying from 15.9 m to 20.2 m are composed of plates in S355 (S460 was only used for column W10) in plate thicknesses up to 100 mm. They have a tubular cross-section with a weight of up to 4,250 kg/m. The steel cross-section is covered with concrete to protect the steel structure against fire (concrete shell thickness minimum approx. 100 mm). The external shape of the columns consists of twisted surfaces. In order not to have to make complex formwork on site, it was decided to add a steel cladding to the steel column cross-section, which acted as formwork. The steel cladding did not extend over the entire length of the column and therefore could not be included as a load-bearing element.

Impact or effectiveness

Floor system: It only makes use of 4 different types of beams. Some of them protrude upwards in the floor system and are integrated, after being fire-protected with intumescent paint, in the raised floor system.
W-columns: Despite the weight and length of the columns (column W10 weighs approximately 80,000 kg), it was possible to supply each column as one element (fig. 21) and assemble it prior to the construction of the temporary work platform.