CCL worked collaboratively with LERA Consulting Structural Engineers to provide the post-tensioned (PT) slab solution for this world-leading oncology research centre in New Jersey. 

‘Building 345’ was designed to promote freedom of movement in an open environment by creating free-flowing workspaces and maximising views of the surrounding landscape. To achieve this vision, all structural support columns were set back 9.1 m from the edge of the building creating long-span cantilevers and large column-free expanses.

This presented a major structural challenge in response to which LERA proposed tapering slab depth from 500 mm at strong column support zones to 200 mm at the perimeter. To control
deflection and provide efficient tensile reinforcement it was clear that bonded post-tensioned concrete slabs would provide the most effective solution.

CCL proposed the use of its XF flat-slab bonded PT system instead of the multistrand PT system of the original design. This simplified the stressing operation due to the strands being individually stressed and avoided the use of heavy multistrand stressing equipment.

The use of two-way post-tensioned slabs helped to avoid the complexities and expenses of fabricating structural steel framing moment connections in two directions. By providing intrinsic fire protection and finishes, the PT system also allowed the floor depth to be minimised and ceiling heights and the open façade to be maximised.

To emphasise the seamless appearance of the glazed façade, the number of façade mullions was minimised, resulting in 4.25 m x 2.1 m glazing panels. By hanging the mullions from the roof slab with only lateral support from the slabs, the impact on the curtain wall caused by movement of the cantilever floors was avoided. The roof slab thickness was increased by 150 mm to support the additional load.

CCL worked closely with all parties to ensure meticulous coordination and sequencing on site.