Which term describes a framework of rafters, posts, and struts that supports a roof, bridge, or other structure?

• A. Beam
• B. Girders
• C. Frame
• D. Truss

Answer: (D)

The idea being tested is recognizing the specific term for a framework made of interconnected straight members that spans and carries loads. This framework, formed by rafters, posts, and struts, is called a truss. A truss uses triangles to keep its shape rigid, allowing it to handle both compression and tension forces efficiently. That triangular design distributes weight from the roof or deck down to the supports, enabling longer spans with less material than a solid beam. In roofs and bridges, trusses rely on multiple members working together, rather than a single beam, to resist bending and sagging. By contrast, a frame is a more general skeleton, a beam is a single horizontal support, and girders are large horizontal members; none inherently convey the same triangular stability that a truss provides.