Bruce S Fairbanks, Architect
Being a liquid material, concrete can be cast into any form allowing it to adapt to structural shapes, minimizing the use of material. At the same time, it can be cast into architectural shapes to resolve functional and decorative issues. In precast concrete design, these concepts can come together; a concrete shape can be given a double purpose serving both architectural and structural requirements.
This paper explores the use of precast concrete in making architectural form and the relationship between architectural and structural form. A selection of three airport control towers demonstrate how the precast concrete systems can be used in the architectural and structural conception of the building.
Control towers are buildings whose functional require- ments play an important part in their final form. The shape and height of the control room and its structural requirements are some of the first elements to be defined based on sight lines and height restrictions. Redundant shafts for high technological services, emergency systems and other complex spatial demands are other issues that need to be resolved in the project phase.
Apart from functional issues, because of its height, the control tower is usually a singular element in an otherwise unbuilt airfield. Airport clients want control towers to become representative elements or even a symbol for the airport, putting additional constraints on their design.
Typically, control towers are composed of a low base building and a tall slender shaft element that supports larger upper floors dimensioned to adapt to the necessity of control operations. The structural system and the construction process for these elements must have important consideration from the beginning of the design process.
The following examples demonstrate different conceptual approaches for designing this building typology, and how precast concrete can be used as a multi-task material capable of resolving structural and architectural demands.