Which bridge type is defined by a load-bearing superstructure composed of a truss?

• A. Arch Bridge
• B. Truss Bridge
• C. Suspension Bridge
• D. Cantilever Bridge

Answer: (B)

Recognizing a truss-based load-bearing superstructure is the key idea. A truss bridge uses a framework of straight members connected to form triangular units, so loads are carried mainly as axial tension or compression in the members rather than bending them. This efficient axial-force transfer is what defines the structure's primary system.

In contrast, arch bridges rely on a curved arch to transfer loads into compression along the arch, suspension bridges hang the deck from cables connected to towers, and cantilever bridges balance loads with overhanging arms. Therefore, the bridge type defined by a load-bearing superstructure composed of a truss is the truss bridge.