Client: State Administration, Erfurt
Architects: Planungsgemeinschaft Pohl & Deyle
Designer: Göran Pohl
Engineers: Arup, Erfurth & Partner
Timber suppliers: Wiehag GmbH, Altheim, Austria
Contractors: Wiesner-Hager Baugruppe GmbH

The requirements for this wide-span covered ice rink led logically to the choice of timber, mainly in the form of glulam. The roof structure, the enclosed space, and the principal dimensions were developed for optimum efficiency and economy of form and assembly. The building, with its 80m span, 186m length and 17m internal ridge height, has a classic shape for a competitive speed skating arena. In cross-section, the structure is developed as a series of flat arches, with 8m headroom at the outer edges of the track.

The main parallel arches span 80m, while the apsidal ends are created by means of two radial series of braced semi-arches with a common profile. At ground level, a reinforced concrete thrust ring is set over piled foundations. Poor soil conditions meant these had to be designed with care and driven deep. The lightness of the timber superstructure was of considerable benefit in reducing foundation pressures.

The straight central portion of the enclosure has its arches spaced at 8.70m. The arches have an interesting and rather unusual structural provision around the curved haunch regions. Here, metal struts are interleaved between inner arch faces, extending up to connect to curved thin glulam secondary chords. This arrangement reduces the depth that would otherwise have been necessary had standard curved glulam portals been used. This elegant device gives the structure an additional sense of freedom and lightness.

At each end of the parallel section are pairs of braced arches at the closer spacing of 5.33m. These form a bracing system that resists the longitudinal wind forces and that passes on, through the purlin arrangements, the main lateral bracing constraints to the rafter portions of the common principal arches. Sixteen structural bays occur within each apse, for here the main bay spacings are halved below the upper purlin levels, thus introducing an extra eight arch ribs. With purlins and lateral members located between the ribs, these end structures provide adequate bracing in themselves for the building to resist transverse wind effects.

Along the length of the hall are five main sets of elements: a roof spine, which has twin members; symmetrical pairs of upper purlin runs, also doubled; and two lower purlin runs. The paired sets at the ridge and upper purlin positions support roof light openings and electrical and lighting services.

For economy of structure, especially at the manufacturing and assembly stages, there is considerable replication. Arch profiles and the secondary roof structures have repeated cross-sections and details. The purlins and bracing blocks comprise adhesive bonded box units, each made up from several individual glulams. This helps conceal services, while ensuring lateral stability.