Multiple-Choice Questions on Design Concrete Structures. Design Concrete Structures Part 1 has 60 MCQs related to designs of Concrete Structures with Answers.

**Design Concrete Structures Part 1**

**Increase in the moisture content in concrete ??**

**a.** does not change the strength

**b.** increases the strength

**c. reduces the strength**

**d.** all of the above

**The property of the ingredients to separate from each other while placing the concrete is called ??**

**a.** bulking

**b.** shrinkage

**c.** compaction

**d. segregation**

**The relation between modulus of rupturefcr and characteristic strength of concrete fck is given by ?? Where fcr and fck are in N/mm2′**

**a.** fcr=1.2Vf7

**b. fcr=0.7Vf7**

**c.** fcr=0.57f7

**d.** fcr=0.35Vf7

**The approximate value of shrinkage strain in concrete is ??**

**a.** 0.03

**b.** 0.00003

**c. 0.0003**

**d.** 0.003

**The approximate value of the ratio between direct tensile strength and flexural strength is ??**

**a.** 1.0

**b.** 0.75

**c. 0.5**

**d.** 0.33

**Workability of concrete is directly proportional to ??**

**a. grading of the aggregate**

**b.** time of transit

**c.** aggregate cement ratio

**d.** all of above

**Air entrainment in the concrete increases ??**

**a.** the unit weight

**b.** the effects of temperature variations

**c.** strength

**d. workability**

**The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by ??**

**a.** fc5>fcr>fC

**b.** fcr<fcs

**c. fcr>fcs>fc**

**d.** tcr – rcs = tct

**Workability of concrete is inversely proportional to ??**

**a.** size of aggregate

**b.** the air in the mix

**c.** ‘water-cement ratio

**d. time of transit**

**Strength of concrete increases with ??**

**a.** decrease in size of aggregate

**b.** decrease in curing time

**c. increase in fineness of cement**

**d.** increase in water-cement ratio

**Part 1 Design Structure MCQs**

**The property of fresh concrete, in which the water in the mix tends to rise to the surface while placing and compacting, is called ??**

**a.** creep

**b.** bulking

**c. bleeding**

**d.** segregation

**As compared to ordinary portland cement, use of pozzolanic cement ??**

**a.** increases strength

**b. increases shrinkage**

**c.** increases bleeding

**d.** reduces workability

**To determine the modulus of rupture, the size of the test specimen used is ??**

**a.** 100 x100 x500 mm

**b. 150 x150 x700 mm**

**c.** 100 x100 x700 mm

**d.** 150 x150 x500 mm

**According to IS: 456 -1978, the modulus of elasticity of concrete Ec (in N/mm2) can be taken as ??**

**a.** Ec = where fck N/mm2 = 700 is the characteristic strength in

**b.** Ec = = 5700fck

**c.** Ec = = 570

**d. Ec = = 5700**

**The percentage of voids in cement is approximately ??**

**a.** 80%

**b.** 60%

**c. 40%**

**d.** 25%

**The most commonly used admixture which prolongs the setting and hardening time is ??**

**a.** sodium silicate

**b.** calcium chloride

**c. gypsum**

**d.** all of the above

**Modulus of rupture of concrete is a measure ??**

**a.** split tensile strength

**b.** compressive strength

**c.** direct tensile strength

**d. flexural tensile strength**

**The strength of concrete after one year as compared to 28 days strength is about ??**

**a.** 25 to 50% more

**b. 20 to 25% more**

**c.** 15 to 20% more

**d.** 10 to 15% more

**In order to obtain the best workability of concrete, the preferred shape of aggregate is ??**

**a.** angular

**b.** elongated

**c. rounded**

**d.** all of the above

**Admixtures that cause early setting and hardening of concrete are called ??**

**a.** air-entraining agents

**b.** retarders

**c. accelerators**

**d.** workability admixtures

**Design Concrete Structures Part 1**

**If the permissible stress in steel in tension is 140 N/mm2, then the depth of neutral axis for a singly reinforced rectangular balanced section will be ??**

**a.** dependent on the grade of concrete also

**b.** 0.45 d

**c. 0.40 d**

**d.** 0.35 d

**As compared to ordinary portland cement, high alumina cement has ??**

**a.** lower initial and final setting times

**b.** higher initial and final setting times

**c.** lower initial setting time but higher final setting time

**d. higher initial setting time but lower final setting time**

**The minimum grade of concrete to be used in reinforced concrete as per IS:456-1978 is ??**

**a.** M25

**b.** M 10

**c.** M20

**d. M15**

**Bulking of sand is maximum if the moisture content is about ??**

**a.** 10%

**b.** 6%

**c. 4%**

**d.** 2 %

**The maximum quantity of water needed per 50 kg of cement for M 15 grade of concrete is ??**

**a.** 34 liters

**b. 32 liters**

**c.** 30 liters

**d.** 28 liters

**1% of voids in a concrete mix would reduce its strength by about ??**

**a.** 20%

**b.** 15%

**c.** 10 %

**d. 5%**

**For concreting of heavily reinforced sections without vibration, the workability of concrete expressed as compacting factor should be ??**

**a. above 0.92**

**b.** 0.85 – 0.92

**c.** 0.80-0.85

**d.** 0.75-0.80

**Finer grinding of cement ??**

**a.** affects only the ultimate strength

**b. affects only the early development of strength**

**c.** both (A. and (B)

**d.** does not affect the strength

**In case of hand mixing of concrete, the extra cement to be added is ??**

**a.** 20%

**b.** 15%

**c. 10%**

**d.** 5%

**Poisson’s ratio for concrete ??**

**a. increases with richer mixes**

**b.** decreases with richer mixes

**c.** remain constant

**d.** none of the above

**Design Concrete Structures Part 1**

**The individual variation between test strength of sample should not be more than ??**

**a.** ±20% of average

**b. ± 15% of average**

**c.** ± 10% of average

**d.** ±5% of average

**The factor of safety for ??**

**a. steel is lower than that for concrete**

**b.** steel is higher than that for concrete

**c.** steel and concrete are same

**d.** none of the above

**For walls, columns, and vertical faces of all structural members, the formwork is generally removed after ??**

**a.** 14 days

**b.** 7 days

**c.** 3 days

**d. 24 to 48 hours**

**The fineness modulus of fine aggregate is in the range of ??**

**a.** 6.0 to 8.5

**b.** 5.0 to 7.0

**c.** 3.5 to 5.0

**d. 2.0 to 3.5**

**The compressive strength of 100 mm cube as compared to 150 mm cube is always ??**

**a. more**

**b.** equal

**c.** less

**d.** none of the above

**One of the criteria for the effective width of flange of T-beam is bf =—+ BW +6Df 6 In the above formula, l0 signifies ??**

**a. distance between points of zero moments in the beam**

**b.** distance between points of maximum moments in the beam

**c.** the effective span of T-beam

**d.** clear span of the T-beam

**If a beam fails in bond, then its bond strength can be increased most economically by ??**

**a.** providing vertical stirrups

**b.** using thicker bars but less in number

**c. using thinner bars but more in number**

**d.** increasing the depth of the beam

** For a continuous slab of 3 m x 3.5 m size, the minimum overall depth of slab to satisfy vertical deflection limits is ??**

**a.** 120 mm

**b.** 100 mm

**c. 75 mm**

**d.** 50 mm

**If the depth of the actual neutral axis in a beam is more than the depth of the critical neutral axis, then the beam is called ??**

**a. over-reinforced beam**

**b.** under-reinforced beam

**c.** balanced beam

**d.** none of the above

**According to IS: 456-1978, the flexural strength of concrete is ??**

**a.** inversely proportional to the square root of compressive strength

**b. directly proportional to the square root of compressive strength**

**c.** inversely proportional to compressive strength

**d.** directly proportional to compressive strength

**Design Concrete Structures Part 1**

**For a cantilever of effective depth of 0.5m, the maximum span to satisfy vertical deflection limit is ??**

**a.** 5 m

**b.** 4.5 m

**c.** 4 m

**d. 3.5 m**

**According to IS: 456-1978, the maximum reinforcement in a column is ??**

**a.** 8 %

**b. 6 %**

**c.** 4%

**d.** 2 %

**Diagonal tension in a beam ??**

**a. increases below the neutral axis and decreases above the neutral axis**

**b.** decreases below the neutral axis and increases above the neutral axis

**c.** is maximum at neutral axis

**d.** remains same

**Which of the following statements is incorrect ??**

**a. The number of longitudinal bars provided in a circular column should not be less than four**

**b.** Reinforcing bars in a column should not be less than 12 mm in diameter

**c.** The spacing of longitudinal bars measured along the periphery of a column should not exceed 300 mm

**d.** The minimum cross-sectional area of longitudinal reinforcement in a column is 0.8%

**According to IS: 456-1978, the column or the strut is the member whose effective length is greater than ??**

**a.** 4 times the least lateral dimension

**b. 3 times the least lateral dimension**

**c.** 2 times the least lateral dimension

**d.** the least lateral dimension

**The minimum pitch of transverse reinforcement in a column is ??**

**a. lesser of the above three values**

**b.** forty-eight times the diameter of transverse reinforcement

**c.** sixteen times the smallest diameter of longitudinal reinforcement bar to be tied

**d.** the least lateral dimension of the member

**For a simply supported beam of span 15m, the minimum effective depth to satisfy the vertical deflection limits should be ??**

**a. 750 mm**

**b.** 900 mm

**c.** 600 mm

**d.** more than 1 m

**A continuous beam is deemed to be a deep beam when the ratio of effective span to overall depth (1/D. is less than ??**

**a.** 3.0

**b. 2.5**

**c.** 2.0

**d.** 1.5

**According to IS 456- 1978, the minimum slenderness ratio for a short column is ??**

**a.** more than 24

**b.** between 18 and 24

**c.** less than 18

**d. less than 12**

**Minimum thickness of load-bearing RCC wall should be ??**

**a.** 200 mm

**b.** 150 mm

**c. 100 mm**

**d.** 50 mm

**The minimum cover in a slab should neither be less than the diameter of the bar nor less than ??**

**a.** 13 mm

**b.** 25 mm

**c. 15 mm**

**d.** 10 mm

**Design Concrete Structures Part 1**

**In reinforced concrete footing on soil, the minimum thickness at the edge should not be less than ??**

**a.** 250 mm

**b.** 200 mm

**c. 150 mm**

**d.** 100 mm

**The ratio of the diameter of reinforcing bars and the slab thickness is ??**

**a. 1/8**

**b.** 1/6

**c.** 1/5

**d.** 1/4

**The slab is designed as one way if the ratio of long span to short span is ??**

**a. greater than 2**

**b.** between 1.5 and 2

**c.** between 1 and 1.5

**d.** less than 1

**The percentage of reinforcement in the case of slabs, when high strength deformed bars are used is not less than ??**

**a.** 1.00

**b.** 0.30

**c. 0.12**

**d.** 0.15

**If the storey height is equal to the length of the RCC wall, the percentage increase in strength is ??**

**a.** 30

**b.** 20

**c. 10**

**d.** 0

**For a longitudinal reinforcing bar in a column, the minimum cover shall neither be less than the diameter of bar nor less than ??**

**a. 40 mm**

**b.** 30 mm

**c.** 25 mm

**d.** 15 mm

**Critical section for shear in case of flat slabs is at a distance of ??**

**a.** at the periphery of column

**b.** at the drop panel of slab

**c. d/2 from the periphery of column/capital/ drop panel**

**d.** the effective depth of slab from the periphery of column/drop panel

**Lap length in compression shall not be less than ??
where (j) is the diameter of the bar**

**a.** 30 (j)

**b. 24 (j)**

**c.** 20

**d.** 15 4>

**The limits of percentage p of the longitudinal reinforcement in a column are given by ??**

**a.** 0.8% to 8%

**b. 0.8% to 6%**

**c.** 0.8% to 4%

**d.** 0.15% to 2%

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