Structural Analysis Multiple Choice Questions on “Classification of Coplanar Trusses”.
1. Simple trusses consist entirely of triangle. True or false?
a) True
b) False
Answer: a
Clarification: It can consists of any other shaped intermediate parts, as long as it is stable.
2. Trusses and frames are different as:-
a) Trusses can bend, frames can’t
b) Both can bend
c) None of them can bend
d) Trusses can’t but frame can
Answer: d
Clarification: Trusses can’t bend but, frames can. Due to this, frames can have bending moments.
3. What is the major difference between truss and beam?
a) Beam can’t transmit load in vertical direction while truss can
b) Truss can’t transmit load in vertical direction while beam can
c) Beam can’t transmit load in axial direction while truss can
d) Truss can’t transmit load in axial direction while beam can
Answer: b
Clarification: Due to its geometry, all bending loads get converted to compressive or tensile load in trusses.
4. A truss formed by joining two or more simple trusses is called:-
a) Simple
b) Compound
c) Complex
d) None of the mentioned
Answer: b
Clarification: Truss formed by joining two or more simple trusses is called compound trusses.
5. If a truss has two more members surpassing each other, then it is:-
a) Simple
b) Compound
c) Complex
d) None of the mentioned
Answer: c
Clarification: Trusses falling into neither simple nor compound are categorized into complex trusses.
B= no. of bars of the truss
R= total no. of external support reaction
J= total no. of joints.
6. If B = 5, R = 3 and J = 4, then the truss is:-
a) Statically determinate
b) Statically indeterminate
c) Stable
d) Unstable
Answer: a
Clarification: B + R = 8 = 2*J. So, truss is statically determinate. Without further insight, we can’t predict stability.
7. If, in the above question R= 4 then the truss are:-
a) Statically determinate
b) Statically indeterminate
c) Stable
d) Unstable
Answer: b
Clarification: B + R = 9 > 2*J. So, truss is statically indeterminate. Without further insight, we can’t predict stability.
8. If, in the above question R = 3 then the truss is:-
a) Statically determinate
b) Statically indeterminate and stable
c) Stable
d) Unstable
Answer: d
Clarification: B + R = 7 < 2*J. So, the truss will be unstable.
9. A simple truss will be always internally stable.
State whether the above sentence is true or false.
a) True
b) False
Answer: a
Clarification: A simple truss starts with a triangle which is internally stable. Then we add rigid elements to it, so there is no scope of relative movement/deformation.
10. If a truss is internally unstable, then we should use it when it is:-
a) Statically determinate
b) Statically indeterminate
c) Statically determinate or statically indeterminate
d) We must never use it
Answer: d
Clarification: If a truss is internally unstable then its use must always be avoided.