School complex Ort, Au-Wädenswil

The project
A complex structural system has been constructed in the Au district of Wädenswil: In the new extension to the Ort Primary School, the use of wood has created both structural and aesthetic highlights. In collaboration with the architectural office horisberger wagen architekten gmbh, Zurich, a structural system featuring Vierendeel trusses was developed. Five floor-to-ceiling beams span the triple-purpose sports hall while simultaneously defining the spatial structure of the floor above, which is used for classroom instruction. The use of wooden Vierendeel trusses demonstrates how high structural requirements can be consistently met in timber construction.

The construction method
The triple-purpose gymnasium is spanned by a raised beam system with a 28-meter span, whose deliberate pre-curvature levels out under the ceiling’s own weight. The roof load is transferred via 38-meter-span wooden Vierendeel trusses with upper and lower chords, as well as CLT shear panels. The force flow is ensured by specially developed wood-to-wood connections using shear cams.

The challenge
The biggest challenge lay in the design of the Vierendeel trusses in the timber structure: long spans, complex shear and tensile forces, and the combination of glulam and CLT had to be addressed with precision. Curved trusses, shear cams, and rigid joints were key factors in the project’s success.