Design & Technology of Concrete Structures Civil Engineering Questions and Answers Part-3

This is the civil engineering questions and answers section on Concrete Structures Design with explanation for various interview questions

Design & Technology of Concrete Structures Civil Engineering

101. The depth of footing for an isolated column is governed by
i) maximum bending moment
ii) shear force
iii) punching shear The correct answer is
a) only (i)
b) (i)and(ii)
c) (i) and (iii)
d) (i), (ii) and (iii)
Ans: d

102. If the foundations of all the columns of a structure are designed on the total live and dead load basis, then
a) there will be no settlement of columns
b) there will be no differential settlement
c) the settlement of exterior columns will be more than interior columns
d) the settlement of interior columns will be more than exterior columns
Ans:c

103. To minimise the effect of differential settlement, the area of a footing should be designed for
a) dead load only
b) dead load + live load
c) dead load + fraction of live load
d) live load + fraction of dead load
Ans: c

104. The critical section for finding maximum bending moment for footing under masonry wall is located
a) at the middle of the wall
b) at the edge of the wall
c) halfway between the middle and edge of the wall
d) at a distance equal to effective depth of footing from the edge of the wall
Ans: c

105. In a pile of length /, the points of suspension from ends for lifting it are located at
a) 0.207 1
b) 0.25 /
c) 0.293 /
d) 0.333 /
Ans: a

Design & Technology of Concrete Structures

106. During erection, the pile of length / is supported by a crane at a distance of
a) 0.207 /
b) 0.293 /
c) 0.7071
d) 0.793 /
from the driving end of pile which rests on the ground
Ans: c

107. While designing the pile as a column, the end conditions are nearly
a) both ends hinged
b) both ends fixed
c) one end fixed and other end hinged
d) one end fixed and other end free
Ans: c

108. The recommended value of modular ratio for reinforced brick work is
a) 18
b) 30
c) 40
d) 58
Ans: c

109. According to ISI recommendations, the maximum depth of stress block for balanced section of a beam of effective depth d is
a) 0.43 d
b) 0.55 d
c) 0.68 d
d) 0.85 d
Ans: a

110. Assertion A : The load factor for live load is greater than that for dead load.
Reason R : The live loads are more uncertain than dead loads.
Select your answer based on the coding system given below :
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.
Ans: a

111. The centroid of compressive force, from the extreme compression fiber, in limit state design lies at a distance of
a) 0.367 xu
b) 0.416 xu
c) 0.446 xu
d) 0.573 xu
where xu is the depth of neutral axis at the limit state of collapse
Ans: b

112. The design yield stress of steel according to IS: 456-1978 is
a) 0.37 fy
b) 0.57 fy
c) 0.67 fy
d) 0.87 fy
where fy is the characteristic yield strength of steel
Ans: d

113. According to Whitney’s theory, ultimate strain of concrete is assumed to be
a) 0.03%
b) 0.1%
c) 0.3%
d) 3%
Ans: c

114. According to Whitney’s theory, depth of stress block for a balanced section of a concrete beam is limited to
a) 0.43 d
b) 0.537 d
c) 0.68 d
d) 0.85 d
where d is effective depth of beam[ES 2k]
Ans: b

115. The load factors for live load and dead load are taken respectively as
a) 1.5 and 2.2
b) 2.2 and 1.5
c) 1.5 and 1.5
d) 2.2 and 2.2
Ans:b

116. As per Whitney’s theory, the maximum moment of resistance of the balanced section of a beam of width b and effective
depth d is given by
a) ^acybd2
b) ^acybd2
c) 0.185acybd2
d) 0.43acybd2
where acy is the cylinder compressive strength of concrete
Ans: b

127. The effect of creep on modular ratio is
a) to decrease it
b) to increase it
c) either to decrease or to increase it
d) to keep it unchanged
Ans: b

128. Shrinkage of concrete depends upon
i) humidity of atmosphere
ii) passage of time
iii) stress The correct answer is
a) (i) and (ii)
b) (ii) and (iii)
c) only (iii)
d) All (i), (ii) and (iii)
Ans: a

129. Due to shrinkage stresses, a simply supported beam having reinforcement only at bottom tends to
a) deflect downward
b) deflect upward
c) deflect downward or upward
d) none of the above
Ans: a

130. In symmetrically reinforced sections, shrinkage stresses in concrete and steel are respectively
a) compressive and tensile
b) tensile and compressive
c) both compressive
d) both tensile
Ans: b

131. A beam curved in plan is designed for
a) bending moment and shear
b) bending moment and torsion
c) shear and torsion
d) bending moment, shear and torsion
Ans: d

132. In a spherical dome subjected to concentrated load at crown or uniformly distributed load, the meridional force is always
a) zero
b) tensile
c) compressive
d) tensile or compressive
Ans: c

133. Sinking of an intermediate support of a continuous beam
i) reduces the negative moment at support
ii) increases the negative moment at support
iii) reduces the positive moment at center of span
iv) increases the positive moment at center of span The correct answer is
a) (i) and (iii)
b) (i)and(iv)
c) (ii) and (iii)
d) (ii) and (iv)
Ans: b

134. The maximum value of hoop compression in a dome is given by
a) wR / 4d
b) wR/2d
c) wR/d
d) 2wR/d
where, w = load per unit area of surface of dome R = radius of curvature d = thickness of dome
Ans: b

135. In a spherical dome the hoop stress due to a concentrated load at crown is
a) compressive everywhere
b) tensile everywhere
c) partly compressive and partly tensile
d) zero
Ans:b

136. In a ring beam subjected to uniformly distributed load
i) shear force at mid span is zero
ii) shear force at mid span is maximum
iii) torsion at mid span is zero
iv) torsion at mid span is maximum The correct answer is
a) (i) and (iii)
b) (i)and(iv)
c) (ii) and (iii)
d) (ii) and (iv)
Ans:a

137. In prestressed concrete
a) forces of tension and compression change but lever arm remains unchanged
b) forces of tension and compressions remain unchanged but lever arm changes with the moment
c) both forces of tension and compres-sion as well as lever arm change
d) both forces of tension and compres-sion as well as lever arm remain unchanged
Ans: b

138. The purpose of reinforcement in prestressed concrete is
a) to provide adequate bond stress
b) to resist tensile stresses
c) to impart initial compressive stress in concrete
d) all of the above
Ans: c

139. Normally prestressing wires are arranged in the
a) upper part of the beam
b) lower part of the beam
c) center
d) anywhere
Ans: b

140. Most common method of prestressing used for factory production is
a) Long line method
b) Freyssinet system
c) Magnel-Blaton system
d) Lee-Macall system
Ans:a

141. Select the incorrect statement
a) The loss of prestress is more in pre-tensioning system than in post-tensioning system.
b) Pretensioning system has greater certainty about its durability.
c) For heavy loads and large spans in buildings or bridges, post-tensioning system is cheaper than pretensioning system
d) none of the above
Ans:d

142. Which of the following losses of prestress occurs only in pretensioning and not in post-tensioning ?
a) elastic shortening of concrete
b) shrinkage of concrete
c) creep of concrete
d) loss due to friction
Ans: a

143. Prestress loss due to friction occurs
a) only in post-tensioned beams
b) only in pretensioned beams
c) in both post-tensioned and preten-sioned beams
d) none of the above
Ans:a

145. Which of the following has high tensile strength ?
a) plain hot rolled wires
b) cold drawn wires
c) heat treated rolled wires
d) all have same tensile strength
Ans: b

146. High carbon content in the steel causes
a) decrease in tensile strength but increase in ductility
b) increase in tensile strength but decrease in ductility
c) decrease in both tensile strength and ductility
d) increase in both tensile strength and ductility
Ans:b

147. Stress strain curve of high tensile steel
a) has a definite yield point
b) does not show definite yield point but yield point is defined by 0.1% proof stress
c) does not show definite yield point but yield point is defined by 0.2% proof stress
d) does not show definite yield point but yield point is defined by 2% proof stress,
Ans: c

148. Select the correct statement
a) Elastic modulus of high tensile steel is nearly the same as that of mild steel.
b) Elastic modulus of high tensile steel is more than that of mild steel.
c) Carbon percentage in high carbon steel is less than that in mild steel.
d) High tensile steel is cheaper than mild steel.
Ans:a

149. Cube strength of controlled concrete to be used for pretensioned and post-tensioned work respectively should not be less than
a) 35 MPa and 42 MPa
b) 42 MPa and 35 MPa
c) 42 MPa and 53 MPa
d) 53 MPa and 42 MPa
Ans: b

150. Ultimate strength of cold drawn high steel wires
a) increases with increase in diameter of bar
b) decreases with increase in diameter of bar
c) does not depend on diameter of bar
d) none of the above
Ans: b