An international recognition of excellence for bureau greisch’s innovation

    Bureau greisch was awarded an Innovation Award of Excellence by the CTBUH (Council on Tall Buildings and Urban Habitat) for the design of the Adaptive Outriggers for the Silver Tower building in Brussels.

    The CTBUH is the leading international organization in the field of high-rise building development. The CTBUH Awards program rewards projects or individuals who have made a significant contribution to the technical development of this type of construction.

    This award is a recognition of the expertise acquired by Bureau greisch in the design of these works.

    Our colleagues Amaury Leroy and Luis Nosiglia will present this innovation at the 2021 Tall + Urban Innovation Conference from May 18th to 20th, 2021. This conference was to be held in Chicago but, due to sanitary conditions, it will be held by videoconference.

    Adaptative Outriggers – Silver Tower

    The Silver Tower, recently renamed Iris Tower, is 137m high in the North district. It has recently hosted the Brussels Regional Public Service.

    The elliptical geometry of the structure gives it great rigidity in the longitudinal direction and great flexibility in the transverse direction, which also corresponds to the greatest wind resistance. To improve the lateral rigidity and flexural strength of the building, eight outriggers (brackets) are placed at the mid-height of the tower to connect the central core to the peripheral columns so that they participate in the overall flexural recovery of the building.

    One of the design challenges of outrigger systems is to integrate the long-term differential deformations that can occur between the columns and the core as a result of creep and shrinkage. A common solution to this problem is the integration of hydraulic devices in the peripheral columns. This has some disadvantages: the jacks must be sized to accommodate the high loads of the columns, cost, difficulty of replacement.

    The adaptive outriggers developed by bureau greisch at the Silver Tower present an innovative and elegant solution in which extension devices are integrated at the level of the brackets themselves.

    The outriggers consist of four elements arranged in a diamond shape and assembled by means of axes. Top and bottom flanges connect at their ends to the columns and core. In the center, an elongation adjustment device (similar to a hydraulic jack) connects the two flanges and allows an automatic control of the differential effects. This particular geometry gives the brackets the possibility to lengthen in the long term by adjusting (shortening) the lengthening device, and therefore to allow a differential core-column settlement without flanging. Elongation devices automatically regulate the length of the brackets, adjusting automatically as needed over the life of the building.

    Our congratulations and thanks go to our partners Ghelamco / Atelier d’Architecture de Genval / Accarain-Bouillot / CIT-Blaton.

    Discover an abstract of the presentation that will be made in May here