Composite Structural Steel Beams and Deck

Structural Behavior:

Composite construction refers to two load-carrying structural members that are integrally connected and deflect as a single unit. For composite beams, the two load carrying members are the structural steel beam and the concrete on composite metal deck with the shear studs being the element that connects them.

Utilizing composite action creates a stiffer, lighter and less expensive structure than if the two elements were not integrally connected and makes this system one of the choice options for commercial construction.

Composite Deck:

Typically accompanying composite steel beams is composite deck. Composite deck utilizes the steel deck and the concrete slab to form an integral unit that plays upon the concretes compressive strength and the steel decks high tensile strength. The element that integrally connects these two components are the steel embossment in the metal deck.

Advantages of Composite Construction

  • Reduced structural steel frame cost compared to non-composite steel construction.
  • Reduction in time and labor cost due to composite deck serving as both the form deck (which in most cases does not require shoring) and the positive reinforcement in the final structure.
  • Compared to cast-in-place construction which requires shoring and re-shoring, composite construction can drastically reduce the construction schedule.
  • Reduction in weight of structural steel frame which also can lead to a less costly foundation.
  • Reduced live load deflection and improved vibration performance due the composite construction being stiffer than comparable systems.
  • Potential for shallower beams which can reduce building height.
  • Increased span lengths are possible.

Disadvantage of Composite Construction

  • Material cost typically higher compared to cast-in-place concrete systems.
  • Installation of shear connectors requires specialized equipment (automatic stud welders) which typically mean having to bring on a speciality sub-contractor.
  • Introduction of camber can create issues with concrete levelness and finishing.

Shear Stud Installation:

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