AISC Column Design Logic Makes Sense for Composite Columns, Too

Structural engineers of North America have regarded the composite column generally as a curious stepchild who does not quite belong to a family, yet appears to behave very well. Fathers of the American Concrete Institute have provided shelter by permitting their own ACI routines to be applied to "concrete compression members reinforced longitudinally with structural steel shape, pipe, or tubing." As a "concrete compression member" the stepchild is restrained from doing its own thing as effectively as its structural steel cousins are allowed to do. The ACI Building Code forbids consideration of axially loaded columns by insisting that all columns also function as beams. Within the structural steel shape and tubing family, compression members can be assembled for design as axially loaded columns. Composite columns that are incorporated into structures with connections identical to those used for steel shapes or tubes ought to be considered analytically to behave exactly the same as the shapes or tubes.