Which type of bridge has the load-carrying member simply supported at both ends?

• A. Through Bridge
• B. Deck Bridges
• C. Simply Supported Bridges
• D. Cantilever Bridges

Answer: (C)

End support conditions determine how a bridge carries loads. When the load-carrying member is simply supported at both ends, each end rests on a support that allows rotation and does not resist bending moment. There is vertical reaction but no moment transfer across the supports, so the member behaves like a simply supported beam. This is the defining feature of a simply supported bridge.

In such bridges, the bending moment is zero at the supports and reaches a maximum near midspan under typical loads, making the analysis straightforward and statically determinate. Cantilever bridges, by contrast, rely on a fixed end that resists moment, not just vertical support, so they’re not simply supported at both ends. Deck versus through describes where the deck is located relative to the supporting framework rather than the end support conditions, so the term simply supported at both ends specifically points to the end supports behaving as pins/rollers without moment resistance.