“La Cloche d’Or” glass canopies in Luxembourg

    “La Cloche d’Or” glass canopies in Luxembourg

    Located in the centre of the fast-developing Cloche d’Or district, the new shopping centre of the same name is a veritable heart of the city. A total of five glass roofs have been installed to provide maximum natural light to the 75,000 m² mall.

    The complexity of the inclined structures required extensive 3D modelling and careful consideration of the concept of the nodes themselves. Several design and parameterisation alternatives were put on the table before arriving at an optimal proposal; the external diameter of the central cylinder finally coincides with 80% of the structure’s nodes, without the bars meeting.

    Once the node concept had been established, the assembly options had to be studied to minimise the need for on-site welding. The solution chosen, which alternates between welding and concealed assembly, not only simplified assembly, but also made it easier to transport the structure to site. Each node is studied individually using parametric research to avoid interference between the bars and to ensure the visual finesse of the attachment of the elements to each other.

    In the end, two types of structure stand out:

    three of the canopies are gridshell. To favour normal forces in the elements and limit bending forces (and therefore the inertia of the metal elements) and to ensure the structural and aesthetic lightness of the whole, the ring beam is stiffened. This choice makes it possible to limit the forces transmitted to the concrete risers that support the whole structure.

    The two remaining canopies, which are longer, have a mixed configuration, with an arched central section and gridshell ends. Again, with a view to limiting the stresses transmitted to the concrete, a minimum number of discreet tie rods have been added in the central section in order to link the edges together and retain the light sections of the profiles.

    The glass roofs are self-stabilising thanks to the perimeter ring, which allows the load to be taken up by the vacuum and are simply installed on the roof.

    The steel used – over 110 tonnes in total – is S355. The tubular sections for the arches are 160x80x4. The diameter of the edge tubes varies between 219×12.5 and 323×16, depending on the canopies.

    The choice of steel is entirely justified in terms of meeting the architect’s criteria for clarity and transparency.

    Mission

    Study of the glass roof frames

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