QUIZ : CIVIL ENGINEERING (13 MAY 2021)

Quiz: Civil Engineering
Exam: DFCCIL-JE
Topic: MISCELLANEOUS

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes

Q1. When HYSD bars are used in place of mild steel bars in a beam, the bond strength
(a) does not change
(b) increases
(c) decreases
(d) becomes zero

Q2. Kinematic viscosity of gases on increase of temperature
(a) decreases
(b) increases
(c) remains the same
(d) none of these

Q3. If the dynamic viscosity of a fluid is 0.5 poise and specific gravity is 0.5, then kinematic viscosity of that fluid in stokes is
(a) 0.25
(b) 0.50
(c) 10
(d) None of these

Q4. If the relationship between the shear stress τ and the rate of shear strain du/dy is expressed as
τ=k(du/dy)^n
Then the fluid with a value of exponent n > 1 is known as
(a) dilatant fluid
(b) pseudoplastic fluid
(c) Newtonian fluid
(d) Bingham plastic

Q5. The radius of Mohr’s circle of stress of a strained element is 20 mm and minor principal tensile stress is 10 N/mm². The major principal stress is
(a) 30 N/mm²
(b) 50 N/mm²
(c) 60 N/mm²
(d) 100 N/mm²

Q6. The principal stresses σ_1,σ_2 and σ_3 at a point respectively are 80 MPa, 30 MPa and – 40 Mpa. The maximum shear stress is
(a) 25 MPa
(b) 35 MPa
(c) 55 MPa
(d) 60 MPa

Q7. According to IS classification, the range of silt size particles is
(a) 4.76 mm to 2.0 mm
(b) 2.00 mm to 0.425 mm
(c) 0.425 mm to 0.075 mm
(d) 0.075 mm to 0.002 mm

Q8. The plasticity index and the percentage of grain size finer than 2 microns of a clay sample are 25 and 15, respectively, its activity ratio is
(a) 2.5
(b) 1.67
(c) 1.0
(d) 0.6

Q9. An undisturbed soil sample has a plastic limit of 25%, a natural moisture content of 40% and liquidity index of 50%. It liquid limit in % will be
(a) 50
(b) 55
(c) 60
(d) 75

Q10. A soil mass contains 40% gravel, 50% sand and 10%, silt. This soil can be classified as
(a) silty sandy gravel having coefficient of uniformity less than 60.
(b) silty gravelly sand having coefficient of uniformity equal to 10.
(c) gravelly silty sand having coefficient of uniformity greater than 60
(d) gravelly silty sand and its coefficient of uniformity cannot be determined.

Solutions

S1. Ans.(b)
Sol. When HYSD bars are used in place of mild steel bars bond stress increased by 60% and bars in compression bond stress increased by 25%.

S2. Ans.(b)
Sol. In case of gases the cohesion forces and small and molecular momentum transfer predominates with increase in temperature molecular momentum transfer increases and hence kinematic viscosity increase.

S3. Ans.(c)
Sol. dynamic viscosity (µ) = 0.5 poise
= 0.5 Ns/m^2
G = 0.5
ρ = 0.5 × 1000 = 500 kg/m^3
Kinematic viscosity (V) = µ/ρ
= 0.5/500
= 10^(–3) m^2/sec
= 10 cm^2/sec = 10 stokes

S4. Ans.(a)
Sol. τ = k(du/dy)^n
If n > 1 then dilatants fluid.
If n < 1 then pseudo plastic fluid.

S5. Ans.(b)
Sol. Radius of mohr circle =(σmax-σmin)/2
20=(σmax-10)/2
▭(6max=50N\/mm^2 )

S6. Ans.(d)
Sol. σ_1=80 MPa
σ_2=30 MPa
σ_3=-40 MPa
Maximum shear stress =(σ_1-σ_3)/2
=(80-(-40))/2
=60MPa

S7. Ans.(d)
Sol. Gravel → 4.75 to 80mm
Sand → 0.075 to 4.75mm
Silt → 0.002 to 0.075mm
Clay → <0.002mm

S8. Ans.(b)
Sol. Activity =I_p/C
I_p- Plasticity index
C- percentage of clay particle
Activity =25/15=1.67.

S9. Ans.(b)
Sol. w_p=25%
w=40%
I_L=50%
w_L=?
Liquidity index 〖(I〗_L)=(w-w_p)/(w_L-w_p )
50=(40-25)/(w_L-25)
▭(W_L=55%)

S10. Ans.(c)
Size Soil % Retained Cumulative % N=100-cumulative
4.75 Gravel 40% 40% 60%
0.075 Sand 50% 90% 10%
0.002 Silt 10% 100% 0%
Coefficient of uniformity (Cu)=D60/D10
=4.75/0.075
=63.33