Some Design Considerations for Composite-frame Structures

Over the past 25 years, numerous innovative structural systems have evolved in tall building design where structural steel and reinforced concrete have been combined to produce a building having the advantages of each material. The use of these so-called composite-frame structures has as its underlying principle the combination of these two distinctive and different building materials to benefit from the advantages of both—namely, the inherent stiffness and economy of reinforced concrete and the speed of construction, strength and light weight of structural steel. The term composite-frame structure has taken on numerous meanings in recent years in utilizing several different building materials. As used here, it is taken to mean a building employing a structural steel and composite metal deck floor system and concrete encased steel columns. The composite beams use headed studs (shear connectors) to achieve composite action between the steel and concrete. The bare steel columns carry the initial gravity, construction and lateral loads until such time as the concrete is cast around them to form composite columns capable of resisting the total gravity and lateral loads of the completed structure.