What do you call the top or bottom section of a trussed beam?

The correct term for the top or bottom section of a trussed beam is known as a "rail." In the context of a truss, the rails are crucial components that help provide stability and structural integrity. The top rail, often referred to as the top chord, and the bottom rail, or bottom chord, work together to form a rigid framework that can distribute loads effectively. Understanding the terminology of a trussed beam is essential for firefighters when assessing building construction and identifying potential hazards during fire operations.

The other terms in the choices refer to different components or structures: a beam is a general term for a structural element that supports weight, grade refers to the elevation or slope of land, and an I-beam is a specific type of beam characterized by its I-shaped cross-section, commonly used in construction. Each of these has distinct properties and uses but does not describe the parts of a trussed beam directly.