A type of column that incorporates two materials or elements of design in its structure is a composite column. The term composite column, as applied in architecture, may refer to a column of the composite order. In engineering, a composite column may also be understood to mean a column of concrete reinforced by a steel core. The latter type of composite column is often used in construction due to its structural advantages, including corrosion protection and increased strength.
Composite columns of classical architecture were developed by the ancient Romans and are so named because they are a combination of two of the classical orders: the Corinthian order and the Ionic order. Each classical order has specific mathematical and aesthetic rules pertaining to its design — for example, a composite column has a height equal to ten of its diameters. It is perhaps easiest to recognize the orders on the basis of their columns, however. Ionic columns incorporate scroll-like designs called volutes, on their capitals, or tops, while Corinthian columns culminate in an acanthus foliage design. Composite columns include both volutes and the acanthus leaves in the capital.
Although classical orders are still widely drawn on even today in architectural design, the term composite column has taken on other meanings in modern engineering settings. A composite column, understood in this sense, is a column that includes a steel core surrounded by concrete. The concrete may either be solidly filled in around the steel section or may simply encase the steel inside a hollow space, reinforced by other internal support. These structures are intended to be load-bearing and have many advantages over plain steel or concrete.
The steel backbone of a composite column lends it increased strength and resistance to buckling. At the same time, the concrete provides protection for the steel infrastructure, preventing corrosion and fire damage. It is also easier to control the specifications of the internal design of these columns to create identical structures for repeating floors in high-rise buildings, which helps simplify the building process and decrease costs.
Use of composite columns allows the construction work itself to be staggered. The steel core can be erected first to support the building’s structure, and then filled in with concrete later. Since steel is lighter than concrete but also stronger, the necessary support structures are smaller and more lightweight than they would be if only concrete were being used. These advantages make composite columns an efficient and economical solution for large-scale construction projects.