This paper describes the redevelopment of Unilever House in Central London, focusing on the detailed design of the atrium structures. The original 1930s grade II listed facade was retained along with the original entrance and behind this there were substantial internal modifications including new stability structures, hand dug caissons and a new atrium. Wherever possible the existing structure was retained, reducing the programme and contributing to the building's BREEAM 'Excellent' rating. The geometrically complex 'flying carpets' hang in the central atrium, supported by duplex stainless steel rods that are engineered to withstand local fires. Innovative connection details were developed, with multidirectional adjustment capability. Vibration due to pedestrian activity was analysed, and an unusual central staircase arrangement ensured that the design achieves office quality responses on the floors. During the sequential depropping process, the hanger rod forces were accurately tuned in order to minimise the probability of rods becoming slack in service.
Damian Eley, MA (Hons), MPhil, CEng, MIStructE
Ben Tricklebank, MEng (Hons), CEng, MIStructE