Which of the following materials is not used in making trusses?
Try it first: pick an option, then read the explanation.
Correct answer: D. Concrete
Asked in SSC JE 22/01/2018 (Morning)
Detailed Explanation
Truss members carry tension as well as compression, and they are usually long and slender.
Why “Concrete” Is Correct
Timber and steel sections (angles, channels, tubes, bars) carry both tension and compression well and are easy to connect at joints. Plain concrete is very weak in tension and heavy, so it is not used to make truss members. (Reinforced or prestressed concrete trusses are rare special cases.)
Why the Other Options Are Wrong
- A. Wooden struts: Timber trusses are common for roofs.
- B. Metal bars: Steel bars and rods are used, especially as ties.
- C. Channels: Steel channels and angles are the usual truss sections.
Key Point
Trusses: steel or timber. Not plain concrete.
Key Concepts for Students
- Self-weight of a steel roof truss ≈ (L/3 + 5) × 10 N/m² of plan (L = span in m).
- Steel truss members are connected with gusset plates.
- Tubular trusses are light and good in compression.
Practice more: this is question 23 in Beams and Trusses MCQs – Part 2. Try the whole set and check every answer instantly.