21) Loss of prestress due to friction occurs
(a) only in pre-tensioned beams
(b) only in post-tensioned beams
(c) in both pre-tensioned and post-tensioned beams
(d) none of the above
22) The load carrying capacity of helically reinforced column as compared to that of a tied column is about
a) 5% less
b) 10% less
c) 5% more
d) 10% more
23)What is the minimum number of longitudinal bars provided in a reinforced concrete column of circular circular cross-section ?
a) 4
b) 5
c) 6
d) 8
24) For water retaining structures, minimum grade of concrete to be used is
(a) M 15
(b) M 20
(c) M 25
(d) M 40
25) A strap footing is a special type of
a) Strip footing
b) Raft footing
c) Combined footing
d) Spread footing
26) In R.C. footing on soil, the thickness at the edge should not be less than
a) 10 cm
b) 15 cm
c) 20 cm
d) 25 cm
27) High strength steel used in prestressed concrete can take how much maximum strain ?
a) 2%
b) 3%
c) 4%
d) 6%
28) What should be the minimum grade of reinforced concrete in and around sea coast construction ?
a) M 35
b) M 30
C) M 25
d) M 20
29) How is the base-level bending moment of a cantilever retaining wall expressed as a function of its height H ?
a) H
b) H2
c) H3
d) H4
30) For the design of retaining walls, the minimum factor of safety against overturning is taken as
a) 2
b) 1.4
c) 1.5
d) 3.0