Design of Composite Columns: The American Approach

Abstract

The use of composite steel-concrete construction in horizontal structural systems is well established in American practice; about 95% of floor systems in low-rise metal construction are of this type. The use of composite action in vertical elements and lateral resisting systems is less common but has found niche applications in tall buildings and unusual structures. The American Institute of Steel Construction pioneered the development of specifications for steel-concrete composite members in the 1960s and continues to update and improve its design provisions with respect to these members. This paper traces a series of developments, beginning with the AISC 1999 Specification, that have led to more complete treatment of the design of composite columns, extension of provisions to the design of joints, and use of composite construction in seismic design. The use of the new provisions for the design of an encased mega-column is illustrated with a detailed design example.