Prestressed Concrete Structures Multiple Choice Questions on “Material Requirement”.
1. The concrete used in trusses is normally of grade ranging from __________
a) M35
b) M50
c) M40
d) M25
Answer: a
Clarification: Concrete used in trusses is normally of grade ranging from M35 to M60 which can be considered as high strength concrete and this high strength are design mixes which are used for heavy structures.
2. The requirement consists of __________
a) Aluminium bars
b) HYSD bars
c) Torsion bars
d) Wooden bars
Answer: b
Clarification: The reinforcements consists of mild steel or HYSD bars together with high tensile steel wires or cables use in the tie members and the material requirements per truss varies with the span and spans of trusses.
3. The trusses spacing for 6m prestressed bow string truss with cable reinforcement span for 18m material requirement per truss?
a) 338-433
b) 311-234
c) 829-456
d) 675-919
Answer: a
Clarification: The trusses spacing for 6m prestressed bow string truss with cable reinforcement span for 18m material requirement per truss prestressed bow string truss with cable reinforcement span 24m-steel 621-689, 30m-steel 1041-1219.
4. The polygonal built up from blocks with prestressed bottom chord having wire cable for 18m – concrete requirement per truss (m3) is?
a) 2.50
b) 2.63
c) 2.78
d) 2.00
Answer: b
Clarification: The polygonal built up from blocks with prestressed bottom chord having wire cable: for 18m – concrete requirement per truss (m3) 24m-3.85m3, 30m-5.28m3 and the difference in truss is observed for different diameters of wire cables.
5. The truss spacing 12m prestressed bow string of linear element with wire reinforcement (18m) grade of concrete (n/mm2).
a) 30- 40n/mm2
b) 10- 50n/mm2
c) 20- 70n/mm2
d) 40- 90n/mm2
Answer: a
Clarification: 24m = 30-50, 30m = 30-50, weight of truss (Kn) 18m = 7.7-9.1, 24m = 14.9-17.4, 30m = 25.5-29.8 are the different truss spacing for spans prestressed bow string of linear element with wire reinforcement for grade of concrete.
6. Calculate effective length of warehouse shed such that length is given as 2.11m and area is given as 650mm2?
a) 3.28m
b) 4.28m
c) 6.25m
d) 1.37m
Answer: d
Clarification: L = 2.11m, A = 650mm2 = 0.65m2
Effective length = Lc = (0.65×2.11) = 1.37m.
7. Calculate total diameter ratio (d’/D) of reinforced concrete truss member such that the internal diameter is 40mm and external diameter is given as 200mm?
a) 0.6
b) 0.8
c) 0.2
d) 9.6
Answer: c
Clarification: d’ = 40mm, D = 200mm
d’/D ratio = (40/200) = 0.2mm.
8. Calculate moment of reinforced concrete truss such that bending moment is given as 4.3 and breadth is given as 250mm and depth is 200mm, characteristic strength of concrete is 35n/mm2?
a) 0.48
b) 0.56
c) 0.34
d) 0.23
Answer: a
Clarification: Mu = (1.5×4.3) = 6.45knm, b = 250mm, D = 200mm, fck = Mu = (1.5×4.3) = 6.45knm, b = 250mm, D = 200mm, fck = 35n/mm2,
M = Mu /fck b D = (6.45×106/35x250x2002) = 0.48.
9. Calculate the compression moments of reinforced concrete trusses such that compression in the member is 395, characteristic strength is 35n/mm2, breadth is 250mm and depth is given as 200?
a) 0.443
b) 0.338
c) 0.654
d) 0.234
Answer: b
Clarification: Pu = (1.5×395) = 592.5kn, b = 250mm, D = 200mm, fck = 35n/mm2
Pu/fckbD = (592.5×103/35x200x200) = 0.338.
10. Calculate minimum reinforcement of 0.8% in the section such that given breadth is 250mm, Diameter is 200m?
a) 400
b) 600
c) 500
d) 800
Answer: a
Clarification: b = 250mm, D = 200mm
Minimum reinforcement of 0.8% in the section As = (0.8x200x250/100) = 400mm2.