What is the appropriate term for a U-shaped structural member?

The appropriate term for a U-shaped structural member is "channel." A channel is a type of structural steel section that has the shape of a U, which is specifically designed to provide support and rigidity in various construction applications. The vertical legs of the channel help to resist bending and shear forces, making it an essential component in building frameworks, bridges, and other structural applications.

Other terms listed, such as beam, ledger, and joist, refer to different types of structural elements. A beam typically refers to a horizontal structural element that supports loads, while a ledger is a horizontal member used to support another structure, often seen in deck construction or wall framing. Joists are also horizontal members, but they are specifically designed to support floor or ceiling loads, spanning between walls or beams. Each of these elements is integral to construction but serves distinct functions and does not represent the U-shaped profile associated with channel sections.