∂ 2014 ¥ 2
Technology
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In the centre of Zurich, not far from the main railway station, a spectacular office building has recently begun to demonstrate the potential of wood as building material for large urban-scale construction tasks. Shigeru Ban designed this new seven-storey building with its visible wood construction as an addition to the headquarters of the Tamedia publishing company. Similar to traditional Japanese wood buildings, it is devoid of metal hardware connectors. Shigeru Ban’s striking wood structures, among them the Centre Pompidou in Metz, are as famous as his buildings made of cardboard tubes. His design for the Tamedia office building originates in the principles of transparency and structural simplicity. The structure was to permit an assembly process similar to building blocks and feature a comprehensible load-bearing system. Wood elements were to remain exposed. To realize these architectural preconditions by using glue-laminated wood in premium quality for visible application and locking pin connections milled with extraordinary precision comprised a great challenge for all partners involved. Transparent volume in an inner-city context The geometry of the design meets urban planning requirements and the transparent new building follows the block border. It terminates along the northern lot corner and adopts the typical aspects of the Werd quarter with its tall ground floor spaces and mansard roof. The design is complemented by the addition of a top floor to the neighbouring building. Its barrel roof comprised of arched beams distinguishes the addition from the new building formally and structurally. At a first glance its volume doesn’t seem overly spectacular. Yet, upon approaching, the purposely oversized wood construction with connections reminiscent of organic joints becomes visible behind the completely glazed facade. The structure displays itself in a particularly impressive way in the grand foyer and the adjoining areas. The two rows of columns along the eastern perimeter define an area similar to a winter garden and as tall as the
entire building, situated in front of the of fices. This 3.20 m deep “intermediate space” not only serves as a climate buffer and access area. Platforms with offset arrangement offer additional spaces used for meetings and creative breaks. The facade elements of these areas can be drawn upward completely, creating spacious loggias with views towards the river Sihl. A continuous staircase connects the individual platforms and provides access to the office levels. Due to this full-height space, the entire building is equipped with a sprinkler system. Wooden connectors One of Shigeru Ban’s aims was to build the 3 structure in its entirety of wood, similar to traditional Japanese timber buildings. Not only columns and beams, but also joint connectors consist predominantly of wood: instead of screws, nails or steel connectors, special dowels made of beech plywood transmit loads and reinforce construction components. The load-bearing structure with its full-height columns, beam pairs and girders with oval cross-section was created as a precise, CNC milled construction kit and assembled on-site similar to a three-dimensional puzzle. Planning and realization of this ambitious project were a great challenge for the timber engineers and builders. As in previous projects, Shigeru Ban once 4 more collaborated with Hermann Blumer and the Blumer-Lehmann Corporation, jointly responsible for developing the concept. The visible wood components were supposed to appear as natural as possible and require no further treatment or finish. A fullsize mock up served for testing. The spruce timber that was used, 2000 m3 in total, is of high quality and originates in a continuous forest area in Styria located at 1000 m above sea level. Wood frame construction principle The 38.15 m long main tract is comprised of eight wood frames each set apart at 5.45 m. They consist of four columns each connected to a beam pair per floor. The continuous columns terminate at eave height and are
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he “intermediate space” constitutes a T full-height buffer and is situated in front of the office areas. Elevation, Stauffacherquai facade Office space above entrance area Office space, top floor Joint column / beam pair / beech plywood dowel during assembly