Which arch-type bridge uses steel beams encased in concrete?

• A. Jack Arch
• B. Through Arch
• C. Deck Arch
• D. Cantilever Arch

Answer: (A)

The concept being tested is how reinforced concrete is used in arch bridges to form a durable, load-carrying member. In a deck arch bridge, the arch sits below the deck and transfers loads into the supports mainly through compression. Modern deck arches are often built as reinforced concrete, with steel reinforcement embedded inside the concrete, effectively creating steel beams encased in concrete to act as the arch. This combination provides the necessary tensile and compressive resistance in a compact, integrated structure.

Jack arches are typically masonry arches without embedded steel reinforcement, so they don’t emphasize steel-encased members. Through arches have the arch rising above the deck and emphasize the arch geometry rather than the concrete-encased reinforcement concept. Cantilever arches combine cantilever action with an arch but again center on geometry and support arrangement rather than the steel-encased concrete detail.