If a truss has two or more members crossing each other (and is neither simple nor compound), it is:
Try it first: pick an option, then read the explanation.
Correct answer: C. Complex
Asked in SSC JE 24/01/2018 (Morning); SSC JE 27/01/2018 (Evening)
Detailed Explanation
Plane trusses are classified by how they are built up:
- Simple: start with a triangle and add two members and one joint at a time.
- Compound: two or more simple trusses joined by three bars, or by one pin and one bar.
- Complex: anything that cannot be built either way.
Why “Complex” Is Correct
When members cross over each other and the arrangement cannot be formed by the simple or compound procedure, the truss is a complex truss. Complex trusses often cannot be solved directly by joints or sections and need special methods (e.g. Henneberg's method).
Why the Other Options Are Wrong
- A. Simple: A simple truss grows triangle by triangle; crossing members do not fit that pattern.
- B. Compound: A compound truss is two simple trusses connected; that is a different arrangement.
- D. None of these: Complex is the correct term and is listed.
Key Point
Simple → triangles added one by one; compound → simple trusses linked; complex → neither.
Key Concepts for Students
- Many roof trusses (Pratt, Howe, Warren) are simple trusses.
- Fink trusses are often compound trusses.
- Henneberg's (member substitution) method is used for complex trusses.
Practice more: this is question 6 in Beams and Trusses MCQs – Part 1. Try the whole set and check every answer instantly.