Between Structure and Architecture

Abstract

Thanks to their flexibility, lightness and robustness, textile works are often used to cover large spaces. Structural efficiency of tensile structures can usually be related to a double curvature geometry. However, the project of the new Brugge Stadium offers a new challenge: the realisation of a flat façade with porous zebra strips of different porosity. The strips are 45° inclined with alternating porosities to create visual zebra effect during day and night as it permits light to pass from both the inside and the outside. With this choice come several design issues. The porous meshes should be prestressed, with its uncommon angle of 45° oriented mesh and the structural span is too important for existing meshes. Consequently, a close collaboration with textile companies was necessary to develop a mesh tailored on the need of the project and on the architectural design intents. The design process followed several steps, among the most significant : 1) understanding of the structural challenges to develop a new product adapted to the project 2) definition of the design criteria related to the dynamic behaviour of flat facades, 3) comparison of a stiff and a soft supporting structure (straight cables) 3) interface of the façade to the main concrete structure of the stadium. In the final design, the membrane is supported by a steel structure diagonally arranged to follow the pattern of the membrane arranged in 35-metre long strips. The steel beams inclined by 45° are preferred to the cable solution: the complications due to pretension are limited, the connection details can be designed to merge visually with the strips, the forces applied to the concrete structure are limited. A special mesh was developed to guaranty the 45% porosity required by the architect and the structural requirement for a 6m span diagonal strip : this design process hints at future design possibilities for textiles structures that could match the architectural intents with some R&D and a direct collaboration with the textile industries.

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