1. Which of the option is correct for mechanism in truss?
a) M = 2J – 3
b) M < 2J -3
c) M > 2J – 3
d) Over stiff truss is example of mechanism in truss
Explanation: Mechanism means unstable or deficient frame. Number of members in truss when less than 2J-3 is known as mechanism.
2. Which of the following material is not used in making trusses?
a) Wooden struts
b) Metal bars
c) Channel
d) Concrete
Explanation: Concrete is good in compression but weak in tension.
3. The space between adjacent bents in a roof truss is called:-
a) Purlins
b) Bay
c) Knee
d) Braces
Explanation: Space between adjacent bents in a roof truss is called a bay. They are economically spread throughout.
4. In a bridge truss, what is the sequence of load transmission?
a) Stringers to floor beams to side trusses
b) Floor beams to stringers to side trusses
c) Side trusses to stringers to floor beam
d) Side trusses to floor beams to stringers
Explanation: Load on a deck is first transmitted to stringers, hen to floor beams, and finally to side trusses.
5. What is the function of portal in bridge trusses?
a) To resist lateral forces
b) To resist horizontal forces
c) To provide additional stability
d) To allow thermal expansion
Explanation: Portal and sway bracing are there to provide additional stability.
6. A roller is provided at end of a bridge truss to allow thermal expansion.
a) True
b) False
Explanation: A roller provides freedom of deformation in horizontal plane in case of thermal expansion.
7. Pratt, Howe and warren trusses are used for typically hoe much span length?
a) 100 ft
b) 150 ft
c) 200 ft
d) 250 ft
Explanation: These trusses generally use span length of about 200 ft in length.
8. In a truss it is assumes that the members are joined by:-
a) Rough pins
b) Smooth pins
c) Either of them
d) Neither of them
Explanation: It is assumed as such so as to avoid development of bending stresses.
9. There is no bending stresses in truss due to:
a) Assumptions made
b) Design
c) Materials used
d) Neither of them
Explanation: Both the assumptions lead to no bending moments in truss system.
10. Generally, in a truss system compressive parts are thicker than tensile parts.
a) True
b) False
c) Can’t say
d) Depends upon situation
Explanation: Compressive parts are made thicker due to the danger of buckling and instability in them