Which deck type is commonly used for large-span bridges due to its stiffness characteristics?

• A. Orthotropic Steel Deck
• B. Timber Deck
• C. Cast-in-Place Concrete Deck
• D. Corrugated Steel Deck

Answer: (A)

Stiffness and light weight are crucial for large-span bridges, and an orthotropic steel deck delivers both. By using a thin steel plate stiffened with a grid of longitudinal ribs and crossframes, this deck behaves as a rigid panel with very high bending stiffness relative to its weight. That combination minimizes deflection and dynamic amplification under live loads, making long spans feasible without resorting to heavier, slower-to-construct concrete decks. The wearing surface can be placed on top, preserving durability while the structural deck remains efficiently stiff.

Timber decks lack the necessary stiffness and durability for long spans; cast-in-place concrete decks add substantial dead load and slower construction; corrugated steel decks are lighter and economical but don’t provide the same high bending stiffness as an orthotropic deck for very long spans.