A redevelopment of the twin towers on Amsterdam's south axis
The multifunctional project 2Amsterdam involves the redevelopment of two existing office towers dating from 1992, known as the Stibbe and Akzo Nobel towers on Amsterdam's Zuidas business district. Based on the design by KCAP Architects, both towers are being radically renovated by J.P. van Eesteren under an Engineer & Build contract. This is being commissioned by Commerz Real and the developer Provast. VDNDP has taken on the Building engineer elaboration of this project for the phases technical design and design ready for execution.
We asked the following project members to share their experiences about the 2Amsterdam project with us: Coert Verkuijl of KCAP, Frank Pijnappel and Ronald van Emst of J.P. van Eesteren and Don van Dasler, Mahmud Akkoc and Maxime Eindhoven of VDNDP.
Making the impossible possible
Unique to this project is of course the location and the reuse of an existing structure, but creating the new, underground parking garage is truly a structural tour de force. First of all, sheet pile walls are placed around the office tower and, after the application of a gel injection layer as a soil sealer, excavation can be carried out to a depth of eleven meters, allowing the tower to stand as a kind of island in the construction pit. This will create space for a three-layer parking garage. Frank Pijnappel: 'In collaboration with the geotechnical consultant, we developed this construction method to make the parking garage possible. This is quite exciting and unique.' Another special part of this project is the facade. The towers feature a distinct and characteristic facade in which the same facade elements are repeated over and over again. Architect Coert Verkuijl explains: "We chose a sleek and clear facade in one style to create an ensemble. By bringing the complex together in one ensemble, it does not fall away between the larger complexes of Atrium and WTC.'
Bouw Informatie Modelling
The 2Amsterdam project lends itself perfectly to BIM because of the different phases that intertwine, the complexity of the project, different disciplines and the complex installations. Ronald van Emst, BIM director at J.P. van Eesteren: 'All parties work with the same information and see from each other what is happening, it must be transparent for everyone, that is our goal.' To organize BIM well, sufficient communication is essential, something that worked extremely well in this project. Weekly coordination meetings took place in which the Building engineer, structural and installation engineering 3D models were exchanged and coordinated with each other. 'Our preference in these projects in the technical design and engineering design phase is to work with a design agency such as VDNDP, because we can switch faster with them and give a better interpretation of the model and the integral development.' Explains Frank Pijnappel, engineering project coordinator at J.P. van Eesteren. 'If a problem is identified, it can be looked at from all sides. And a solution can be sought together.' Maxime Eindhoven, Building engineer at VDNDP: 'During the coordination meeting, all comments were immediately processed in the model. That way the model always remained accurate and up-to-date.'
''Our preference for these projects in the technical design and execution design phase is to use an elaboration firm such as VDNDP because we can switch faster with them and give a better interpretation of the model and integral elaboration.''
Frank Pijnappel | J.P. van Eesteren
Sustainable measures
The design of 2Amsterdam incorporates several technical solutions that contribute to the sustainability of the building and ensure a pleasant working environment for employees. For example, the roof of the office tower is equipped with solar panels and the buildings are heated and cooled by means of heat and cold storage (WKO). In addition, the choice was made to preserve the concrete shell and efficient lighting that ensure lower energy consumption. Mahmud Akkoc, project manager and BIM manager at VDNDP, says: "At the office tower, the glass facade of the atrium provides plenty of daylight so minimal lighting will be needed in the lobby and on the galleries behind the facade. Wherever possible, LED lighting will also be used.' The facade of both towers features highly insulating and soundproof facade elements that are standardized. Thus, different programs and layouts are possible without further adjustments to the facade. Through these sustainable measures, the aim is to achieve the BREEAM Excellent sustainability label for the office tower.
Cooperation
The cooperation between the various parties went very well. Partly due to the weekly contact during the coordination meeting with the contractor J.P. van Eesteren, structural engineer RHDHV and installer UNICA. Specific technical solutions were thought up and worked out in full. Architect Coert Verkuijl of KCAP did come up with a point for improvement when it came to the collaboration. "We have seen relatively little of your work. In my view, a more intensive collaboration in all areas would have been better.' This comment from KCAP is understandable according to Don van Dasler, senior project leader at VDNDP, because the architect becomes a bit more distant in this form of contract: 'At the beginning of the project VDNDP, together with J.P. van Eesteren, sought contact with KCAP to understand the background of the project. In the further process, the project was developed on that basis. For a future collaboration, more coordination could be even more positive. Both parties believe that the elaboration of the design has been well interpreted by VDNDP.'
The total project comprises approximately 40,000 m2 spread over 19 floors. The western tower will house a four-star hotel from chain Melia and this tower will be raised by three floors, creating unobstructed views of Amsterdam from the skybar. The eastern tower will again provide space for offices. There will be a parking garage under the existing buildings and the surrounding outdoor space will form a semi-public garden. The towers will be connected by means of a glass facade; this so-called "plinth," the carpet pad of both buildings, provides a link between the two towers and thus makes it a physical whole. The project will be completed in 2021.
