250+ TOP MCQs on Construction Features and Answers

Prestressed Concrete Structures Multiple Choice Questions on “Construction Features”.

1. The chords and struts of trusses are designed for convenience in __________
a) Plastering
b) Fabricating
c) Rubbing
d) Forrowing
Answer: b
Clarification: The chords and struts of trusses are designed to have the same width for convenience in fabricating the truss in a horizontal position such that it is protected by external moments and also smoothen the members.

2. The precast roof slabs are used for __________
a) Roof coverings
b) Slab coverings
c) Column coverings
d) Beam coverings
Answer: a
Clarification: If precast roof slabs are used for roof covering the upper chord panels are made equal to the width of the precast slabs which is usually about 3m and the lower tension chord is prestressed using bunched high strength wires or cables running in perforated holes.

3. For spans in the range of 18-24m, the trusses are made in how many pieces?
a) 4 pieces
b) 2 pieces
c) 1 piece
d) 5 pieces
Answer: c
Clarification: For spans in the range of 18-24m, the trusses are made in one piece but when spans run from 24-30m, they are made in two pieces with a joint at mid span and beyond them they are divided into equal spans and joints are made.

4. The polygonal trusses with inclined top chords are generally made of __________
a) 8m Blocks
b) 6m blocks
c) 12m block
d) 65m block
Answer: b
Clarification: Polygonal trusses with inclined top chords are generally made of 6m blocks or half trusses with 3m panels and due to higher tensions developed in the diagonal members of large span trusses, prestressing them becomes inevitable.

5. The polygonal trusses are less economical than?
a) Circular
b) Bow type
c) Curved
d) Oval
Answer: a
Clarification: In general polygonal trusses are less economical than the bow type with regard to material and labour costs and various types of trusses like circular, cylindrical, hollow etc used for various structures are not much economical because of their shapes and freeness to work.

6. The steel bearing plates which are anchored serves as __________
a) Loading
b) Bearing
c) Stressing
d) Deforming
Answer: b
Clarification: At the ends of trusses near supports, 10-12mm steel bearing plates are anchored and embedded while casting, which serve as bearing and for fixing the trusses on neoprene pad bearings located on the columns.

7. Calculate the area of concrete section such that loss ratio is 0.18 and compressive strength is 15n/mm² (N_d = 377×10³)?
a) 9.43n/mm²
b) 6.54n/mm²
c) 8.5n/mm²
d) 9.34n/mm²
Answer: a
Clarification: N_d = 377×10³, ɳ = 0.18, f_ct = 15n/mm²
Area of concrete section = (N_d/ɳf_ct) = (377×10³)/0.8×15) = 3.316mm².

8. Calculate the number of wires which are subjected to prestressing force of 471.5kn, the section adopted is 50000 using 7mm diameter high tensile wires initially stressed at 1100n/mm²?
a) 13.2
b) 11.13
c) 24.5
d) 34.2
Answer: b
Clarification: Given section adopted = 50000, prestressing force 471.5kn, using 7mm diameter high tensile wires initially stressed so 1100n/mm²
N = (471.5×10³/38.5×1100) = 11.13.

9. Calculate the cracking load such that section adopted is 50000, the loss ratio is 0.8, compressive strength of concrete is 9.43 and minimum reinforcement is 4.0mm²?
a) 455kn
b) 324kn
c) 577.2kn
d) 456.6kn
Answer: c
Clarification: The cracking load = (50000 (0.8 x 9.43) + 4.0 / 1000),
Section adapted = 50000, ɳ = 0.8, f_ct = 9.43, A_s = 4.0 (A_s is the minimum reinforcement of 0.8 percent in the section).

10. Which type of analysis should be done which will lead to an optimal design of planning a structure?
a) Comparative analysis
b) Strength analysis
c) Transferred analysis
d) Global analysis
Answer: a
Clarification: It is important to note that there is no single form of design which would be most economical in a given situation and to arrive at an economical design, several alternatives using different materials and structural configurations should be examined and a comparative analysis made which will lead to an optimal design.