Building Construction online quiz on “Trussed Roofs – 2”.
1. In a mansard roof truss, the upper portion consists of a queen-post truss.
a) True
b) False
Answer: b
Clarification: Mansard roof truss is a two-storey truss. The upper portion consists of a king-post truss while the lower portion consists of a queen-post truss.
2. Which of the following types of trusses is in the shape of a bow?
a) Mansard truss
b) King-post truss
c) Queen-post truss
d) Bel-fast truss
Answer: d
Clarification: Bel-fast truss is in the shape of a bow. It comprises of thin sections of timber. This type of truss is also known as bowstring truss or latticed roof truss.
3. Composite roof trusses are made of _____ and ______
a) Timber and steel
b) Timber and wood
c) Timber and sand
d) Sand and steel
Answer: a
Clarification: Composite roof trusses are made of timber and steel. In this type of truss, timber is used to make the compression members while steel is used to make the tension members.
4. Which of the following types of trusses is not a wooden truss?
a) King-post truss
b) Mansard truss
c) Composite truss
d) Truncated truss
Answer: c
Clarification: King-post truss, queen-post truss, mansard truss, truncated truss and bel-fast truss are all examples of wooden trusses. However, a composite truss is made up of timber and steel.
5. In the combination of king-post and queen-post trusses given below, C represents _______
a) King-post
b) Princess post
c) Queen-post
d) Rafter
Answer: b
Clarification: In the combination of king-post and queen-post trusses given above, A represents king-post, B represents queen-post and C represents princess post. A princess post is used to strengthen the queen-post truss for large spans.
6. Timber trusses are not preferred when the span is greater than __________
a) 3 m
b) 5 m
c) 7 m
d) 10 m
Answer: d
Clarification: Timber trusses are not preferred when the span is greater than 10 m. In this case, timber trusses become uneconomical whereas steel trusses are more economical. Hence, steel trusses are used in place of timber trusses.
7. A steel roof truss is designed in such a way that it carries only direct stresses and not binding stresses.
a) True
b) False
Answer: a
Clarification: Steel roof truss is designed in such a way that it carries only direct stresses and not binding stresses. Direct stresses can be either compressive or tensile. Steel roof trusses are usually made of angle sections and plates.
8. Which of the following is not a category of steel trusses?
a) Open trusses
b) North light trusses
c) Bowstring trusses
d) King-post trusses
Answer: d
Clarification: The various categories of steel trusses are open trusses, north light trusses, bowstring trusses and arched rib trusses. King-post trusses are wooden trusses.
9. In a steel roof truss, which of the following is made of single angle sections only?
a) Principal rafter
b) Strut
c) Main tie
d) King-post
Answer: b
Clarification: The principal rafter in a steel roof truss is usually made of two angle sections. The main tie is also made of two angle sections. However, struts are usually made of single angle sections.
10. In steel roof trusses, the diameter of rivets used for large spans is _________
a) 10 mm
b) 15 mm
c) 20 mm
d) 50 mm
Answer: c
Clarification: The number of rivets used at each joint in steel roof trusses should be at least two. For small spans, generally 15 mm diameter rivets are used and for large spans, usually 20 mm diameter rivets are used.
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