With regard to beams in structure, what are joists?
- AUsually indicate a major beam frequently at wide spacing that supports small beams
- BClosely spaced beams supporting the floors and roofs of buildingCorrect
- CRoof beams usually supported by trusses
- DRoof beams usually supported by purlins
Solution
Concept
Beam terminology
Step-by-step solution
1. Joists are closely spaced beams that support floors and roofs. 2. A girder is a major beam at wide spacing carrying smaller beams. 3. A purlin is a roof beam supported by trusses; a rafter is supported by purlins.
Explanation
Joists are light, closely spaced beams that carry the floor or roof deck directly.
Why the other options are wrong
(a) describes a girder, (c) describes a purlin, and (d) describes a rafter.
Shortcut
Joist = closely spaced floor beam.
Common mistake
Choosing girder.
Correct answer: B) Closely spaced beams supporting the floors and roofs of building