Which statement best describes the role of shear connectors in achieving composite action between a concrete deck and a steel girder?

• A. They are used only for decorative purposes.
• B. Shear connectors transfer shear between the concrete deck and steel girder and ensure full composite action.
• C. They prevent any movement between deck and girder.
• D. They are not required for composite action.

Answer: (B)

The key idea is that composite action between a concrete deck and a steel girder relies on a strong interfacial shear connection. Shear connectors provide a path for shear transfer between the deck and girder so the two act together rather than independently. By preventing slip at the interface, they ensure the concrete and steel deform as a single unit, which increases the stiffness, reduces deflections, and raises the ultimate load-carrying capacity of the structure.

Decorative purposes are not the function of these connectors, and they do not entirely lock the deck and girder in place—some controlled slip can occur, but the connectors are designed to transfer interfacial shear and achieve full composite action. They are required to realize the intended composite behavior; without them, the deck and girder would behave more like two separate members with lower stiffness and strength.