Binding and Bonding Concrete to Composite Columns

Composite interaction between concrete encasement and structural steel shapes is limited unless lateral ties and/or mechanical attachments insure such interaction until desired strength levels are reached. Suggestions are offered toward a rational estimate of requirements for lateral ties, their size and spacing being related to the concrete cover thickness beyond the tips of structural shape flanges. The use of reinforcing bars welded longitudinally to the exterior face of a structural shape is encouraged, and suggestions are given for estimating the bond transfer through such bars. Shear friction transfer through transverse tie action also is discussed. The various mechanisms available for shear interaction between the concrete and the steel shape are discussed briefly as they relate to the distribution of floor loads into the composite column.