Which deck type is characterized by being stiffened with ribs and floor beams and is used for enhanced rigidity?

• A. Overlay
• B. Overdriving
• C. Nosing
• D. Orthotropic Deck

Answer: (D)

The main idea here is how stiffness in a bridge deck is achieved by integrating internal members. An orthotropic deck uses a steel deck plate that is stiffened by longitudinal ribs and backed by transverse floor beams, forming a rigid, lightweight panel. This arrangement makes the deck much stiffer in the longitudinal direction, which improves overall rigidity and reduces deflection and vibration under traffic loads. It’s especially advantageous for long-span bridges where a solid concrete slab would be heavier and less efficient, because the rib-and-floor-beam system distributes loads effectively to the supporting girders while allowing a thinner, lighter deck.

Adding a surface overlay only places a new layer on top of an existing deck and doesn’t create the internal stiffness provided by ribs and floor beams. Nosing is a small edge feature and not a deck construction method for increasing rigidity. Overdriving isn’t a deck-type construction term for improving rigidity, so it doesn’t describe a stiffened deck system.