Ancillary components
Ancillary structures in atria, such as stairs and galleries, are often constructed in bare steel.
Atria are usually designed to be outside the fire safety area of a building, all escape routes, stairs and fire-fighting lifts being inside the occupied building. This means that exposed steelwork can be used for supporting galleries, lifts, escalators and stairs, subject only to the concerns of the insurers to minimize losses. Examples include Gateway House II at Basingstoke, where Arup Associates have built an all-steel complex of walkways, lift towers and roof supports inside the atrium.
The State of Illinois Building has steel perimeter walkways and linking stairs, and spectacular steel lift towers free-standing in space-like siege engines.
The Mackenzie Health Sciences building at the University in Edmonton, Alberta, by Eberhard Ziedler has steel lift and stair structures and trussed bridges crossing the atria. Major steel ventilation ducting also passes through the spaces, saving built volume and gaining service flexibility in a more practical way than with the external ducting at Lloyds.
A smaller example of the same philosophy is Jahn's headquarters for Rustoleum Paints, Chicago, which used a steel frame painted with intumescent finish, steel stairs and steel airhandling ducts.
