1 Daytime view. 2 Detail: the consistent 45° angle of the glass fibre-reinforcement and the returned edges of the GRP moulded items in the flange areas are clearly visible. 3 At night the tower is illuminated with LEDs. 4 The D-Tower is made up of 19 individual elements.
Location Doetinchem, Netherlands Material Glass fibre-reinforced epoxy resin Completion 2004
PLASTICS AS BUILDING STRUCTURE
Architecture NOX Architects, Lars Spuybroek Structural engineering Bollinger + Grohmann Ingenieure
The 12 m high tower sculpture is part of an interactive art project. Created together with the artist Q. S. Serafijn, the concept involved the local residents, who were asked to answer regular questionnaires. Their responses were then analysed by computer to determine the general emotional state of the community. The currently predominant emotion is represented by a colour that is then used to illuminate the tower in the evening. The translucent tower consists of 19 individual pieces manufactured out of glass fibre-reinforced epoxy resin. The complex geometry of the tower can be reduced through the repetition of individual elements to seven basic forms. The stability of the self-supporting GRP structure is ensured through the doublecurved geometry of the skin, reinforcing ribs in the upper section and restraints in the columns. The four columns take the form of tubes with flanges at their bases,
which are used to bolt the tower to the concrete foundation. The individual elements were made manually in a hand lay-up process. This method made it possible to vary the thickness of the material as required. For the moulds, Styrofoam blocks were cut to shape with the help of a CNC milling machine and coated with a latex separating layer. The partial repetition of some
Assembly No. of parts - 19 Total surface area - 193.5 m2
of the elements made it possible to re-use the individual moulds. Despite being more expensive than polyester resin, epoxy resin was chosen for the laminate for its superior dimensional stability during the hardening process. This made it possible to produce GRP elements of different thicknesses. A further reason for choosing epoxy resin was its greater strength. The material thickness in the upper shelllike sections is 4.5 mm. The glass fibre context varies according to the load that has to be sustained. Wind loads proved to be the critical load case in the structural design of the elements. Additional layers of fibre have been incorporated for added strength along the returned edges of the elements as well as in the columns and the base flanges. The segments are both bonded and bolted to one another along their returned edges. With a total surface area of 193.5 m2, the tower weighs approximately 3000 kg. The tower was prefabricated in two halves before being transported to the site on the back of a large lorry. LEDs installed in small niches illuminate the tower at night in different colours.
Published on Oct 1, 2010
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