bar joist

A bar joist, also known as an open web joist, is a lightweight and efficient structural component used in building construction to support roofs and floors. It is a type of truss, typically made with angles for the top and bottom chords, connected by a web of bent rod. Bar joists are designed to span significant distances, with some capable of spanning up to 45 meters (150 feet). They are commonly used in low-rise commercial, institutional, and industrial buildings, as well as for supporting roofs. Joists, in general, are parallel supports laid across girders or bearing walls to hold up ceilings or floors.12