Coping with Movement
Because of the deflection of the structure, the system had to be designed to avoid glass failure, due to the issue of racking, a result of adjacent mullions deflecting excessively.
Once the fenestration installation contract was awarded to Vitrine, their design/engineering team embarked on a detailed review of the curtain wall specification. Considered options included strengthening the primary structure, developing a bespoke glazing system, unitised systems, upgrading an existing curtain wall system and bespoke bracketry.
Numerous systems were considered and it became clear that a bespoke solution would need to be considered to accommodate the required deflections.
It was agreed that Novastruct’s FSX 110 Curtain Wall Zone-Drained System should be further investigated. The primary reason for proposing the system was the availability of a 65mm wide system and have also developed and successfully tested an enhanced movement/expansion joint for it.
The glass needed to achieve barrier load performance, and the size and specification of the glazing units pushed the weight capacity beyond Novastruct’s standard curtain walling.
Using its Increased Weight Capacity Console, Novastruct undertook a stringent process of interrogating the structural model to refine the deflections that resulted in the conclusion that bespoke brackets had to be incorporated into the assembly, allowing the curtain wall to be ‘jacked’ during installation. As the facetted, curved-effect curtain wall was loaded, the structure and curtain wall would theoretically deflect, so the brackets would allow the glazing system to be lined and levelled.
A few bracket designs were considered, and a complex, engineered one was finally selected.
Brackets were fixed back to the steel beams below the concrete floor decking. This meant that the distance between the FSX 110 curtain wall and the structure increased substantially, resulting in a bulky bracket to suit the loadings.
For front and rear entrance doors, Vitrine installed Novastruct’s DSX 190 TB all-purpose door with framing. Some doors feature automatic door gear, actuated from the building’s reception desk, supported by an intercom system.
