Case study for ultra high performance concrete
A case study team designed an observation tower for the nature reserve ‘De Onlanden’ near the city of Groningen in the Netherlands. The Dutch Society for the Preservation of Natural Heritage ‘Natuurmonumenten’ received the plan as a gift.
The case study
The study aimed to apply the characteristics of ultra high performance concrete in a functional, operative design. The case study team consisted of designers, engineers and builders from UNStudio, ABT, BAM Utiliteitsbouw en Haitsma Beton. Together they sought a solution through which architecture and construction could reinforce one another. According to Ben van Berkel, 'The observation tower afforded our inventive materials research platform the opportunity to investigate the properties of ultra high performance concrete and to truly test out the full potential of this new material in a real structure.'
Ultra high performance concrete differs from normal concrete as it has a very high density, contains steel fibres and has an extremely fine grain structure. These properties facilitate the application of large compressive stresses in structures of narrow dimensions.
UNStudio’s inventive materials platform is one of four in-house research platforms and aims to investigate custom-made material applications and to facilitate inspired and imaginative collaborations with other experts and with manufacturers in the construction industry.
The observation tower
The 25 metre high observation tower will be realised on the forested boundary of ‘De Onlanden’ nature reserve on the outskirts of Groningen. Once built, the tower will extend 5 metres above the trees and will offer views over the 3,000 hectares of natural landscape which form the largest water storage area in the Netherlands.
The design for the observation tower guides visitors in a fluid ascent up the 134 steps to the highest viewing point. Visitors are lead via the first set of steps to the lower viewing platform which stands at a height of 10 metres. Following this, the second set of steps provides a turn in direction, allowing for an alternative view of the surrounding forested pastures. These steps lead visitors through the tree tops to the second viewing platform which stands at a height of 20 metres and offers views over the nature reserve around the city of Groningen. The highest viewing platform, at a height of 24 metres, is reached via the final set of steps and offers visitors a wide open vista of ‘De Onlanden’ nature reserve.
The observation Tower is a hybrid construction, consisting of a combination of steel and ultra high performance concrete. Steel is employed where the tensile stresses are foremost, whereas ultra high performance concrete manifests excellent performance properties where the compressive stresses are highest. The parapet around the stairs and platforms is constructed from stainless steel mesh, enabling the combination of both maximum transparency and necessary safety levels.
Ben van Berkel: “The Netherlands enjoys a rich and textured natural landscape, but unfortunately the Dutch topography is not very varied; we don’t have mountain ranges, or many hilly areas from which to enjoy a panoramic overview of our natural surroundings. The viewing tower for ‘De Onlanden’ was designed to provide the opportunity to create a new awareness and different perspectives of the landscape we move through, but may otherwise never experience in all its scope.”
‘Natuurmonumenten’ received the plan as a gift on 22 September 2011 during the mini-symposium ‘Experience Nature with innovative concrete’. The case study team comprised of
Observation Tower, 'De Onlanden', Peize, Netherlands, 2011
Location: Outskirts of Drenthe (near City of Groningen, Eelde and Peize)
Height: 25 m
No. of steps: 134
Programme: Observation Tower
UNStudio: Ben van Berkel with Arjan Dingsté and Marianthi Tatari, Marc Hoppermann, Kristoph Nowak, Tomas Mokry, Dorus Faber
Case study partners