Francis Duffy, Architect and Founder of DEGW
Bennetts Associates: Four Commentaries 2005
On a prominent City of London site, this 30,000m2 office building uses its exposed steel frame construction to strike a chord with the similarly expressive Victorian warehouse buildings nearby.
Bennetts Associates’ design strategy places the major cores at the perimeter, leaving the centre of each floor free for the wide, adaptable floors required in major City office buildings. In consequence, the cores play a significant role in the townscape, forming landmarks at key views and junctions without the limitations imposed by regular office fenestration.
Unlike some of the classic exposed steel frame buildings in the US, where a handsome external frame can disguise a concrete-encased structure inside, the external structure at Devonshire Square has the integrity of its load-bearing function. To express this, columns and beams on the facade are not covered with fire protection, but are shielded by the cladding design. The column flanges and the beams – the dimensions of which are large enough to cover the raised floor and ceiling zone – incorporate a degree of redundancy in the structure that assists with fire resistance. The necessary thermal break between each internal beam and the external structure is achieved by a special insulated connection. The technical resolution of the exposed steel frame was critical to finding an appropriate architectural expression for what can often be a bland building type.