SSC-JUNIOR ENGINEER (Civil & Structural) Online Exam 2020 (Exam held on 23/03/2021) (Part-III)

GENERAL ENGINEERING CIVIL AND  STRUCTURAL

Total Questions: 50

21. Which of the following is Kharif season in India?

Correct Answer: D. May/June to October/November
Solution:In India, the season is popularly considered to start in June and end in October. Kharif crops are usually sown at the beginning of the first rains during the advent of the south-west monsoon season, and they are harvested at the end of monsoon season (October-November).

22. Which of the following methods is NOT used for finding deflection of beam?

Correct Answer: D. Moment distribution method
Solution:Slope and deflection are required to be known for the proper design of a beam in order to avoid its failure. Following methods are used to find the slope and deflection of a beam.

(a) Double integration method
(b) Macaulay's method
(c) Moment area method
(d) Conjugate beam method
(e) Method of superposition
(f) Strain energy method

Energy method : Castigliano's theorems

Castigliano's first theorem enunciated in 1879 states that the first partial derivative of the internal strain energy of a linear and conservative structural system taken with respect to the applied load is equal to the deformation of the point of application of the load in the direction of the load. This theorem is applicable to both discrete and continuum systems and is very similar in concept to the unit-load method.

Castigliano's second theorem states that in a linearly conservative system, the partial derivative of strain energy with respect to the deflection is equal to the force applied at that point in the direction of the deflection.

Moment-Area Method

Theorem 1: The change of slope between any two points on an elastic curve of a beam subjected to bending is equal to the area of the M/EI diagram between the two points. M is the bending moment and EI is the flexural rigidity of the member.

Theorem 2: The tangential deviation of a point B on an elastic curve of a beam from the tangent through another point A, also on the elastic curve is equal to the statical moment of the M/El diagram between the two points taken about the point B.

23. In mix design for M25 concrete, the assumed standard deviation for estimation of target mean strength of concrete mix, as recommended by IS 456 : 2000 is (in N/mm²).

Correct Answer: D. 4.0
Solution:In mix design for M25 concrete, the assumed standard deviation for estimation of target mean strength of concrete mix, 4 N/mm².

24. What is the permissible limit of organic matter present in water for mixing concrete as per IS 456-2000?

Correct Answer: A. 200 mg/l
Solution:The water quality for construction shall be tested or monitored regularly, as it affects the overall strength of concrete. For plain and reinforced cement concrete permissible limits for solids in water as per IS: 3025 is as follows.
Types of solid in waterPermissible limits for construction
Organic matter200 mg/l
Inorganic matter3000 mg/l
Sulphates (SO₄)500 mg/l
Chlorides(a) 500 mg/l for RCC work, and
(b) 2000 mg/l for PCC work
Suspended matter2000 mg/l

25. A reinforced concrete beam is subjected to the following bending moments.

Moment due to dead load = 50 kNm

Moment due to live load = 50 kNm

Moment due to seismic load = 20 kNm

The design bending moment for limit state of collapse is:

Correct Answer: C. 150 kNm
Solution:

26. Which of the following actions is NOT a permanent adjustment in case of transit theodolite?

Correct Answer: A. Bringing the vertical axis of the theodolite exactly over the station mark
Solution:The permanent adjustments of theodolites are made to establish fixed relationship between the instrument's fundamental lines. The fundamental lines or axis of a transit theodolite include the following:
  • Vertical axis
  • Axis of plate levels
  • Axis of telescope
  • Line of collimation
  • Horizontal axis
  • Axis of altitude bubble and the vernier should read zero.

These adjustments once made last for a long time. These are important for accuracy of observations taken from the instrument. The permanent adjustments in case of transit theodolite are:

  • Horizontal axis adjustment: The horizontal axis must be perpendicular to the vertical axis.
  • Vertical circle index adjustment: The vertical circle must read zero when the line of collimation is horizontal.
  • Adjustment of altitude level: The axis of altitude level must be parallel to the line of collimation.
  • Collimation adjustment: The line of collimation or line of sight should coincide with axis of the telescope. The line of sight should also be perpendicular to the horizontal axis at its intersection with the vertical axis. Also, the optical axis, the axis of the objective slide, and the line of sight should coincide.
  • Adjustment of horizontal plate levels: The axis of plate levels must be perpendicular to the vertical axis.

27. The soils transported and deposited by a river or a stream are called:

Correct Answer: D. alluvial soils
Solution:Alluvial soils are soils deposited by surface water. You'll find them along rivers, in flood-plains and deltas (like the Mississippi Delta), stream terraces, and areas called alluvial fans. This last category results from larger floods, causing the soil to spread out in the shape of a triangle fan.

28. Select the correct statement with respect to an over-reinforced cement concrete section under the working stress method.

Correct Answer: C. The allowable limiting stress is reached in concrete before the steel stress reaches the limiting value
Solution:An over-reinforced beam is one in which the tension capacity of the tension steel is greater than the combined compression capacity of the concrete and the compression steel (over-reinforced at tensile face). So the "over-rein-forced concrete" beam fails by crushing of the compressive-zone concrete and before the tension zone steel yields, which does not provide any warning before failure as the failure is instantaneous.

29. The amount of cement required for 100 m² area, of damp proof course with 2.5 cm thickness, in with proportion of 1 : 2 : 4 (cement : sand : aggregate) will be:

Correct Answer: B. 0.55 m³
Solution:

30. In which type of estimate is 'Courtyard' NOT considered?

Correct Answer: C. Plinth area estimate
Solution:Plinth-area estimate: This estimate is prepared on the basis of plinth area of the building. The plinth area rate is obtained from the cost of similar building having similar specifications, height and construction in the locality.

Plinth area is the built-up covered area of a building measured at floor level of any storey. It is calculated by taking the external dimensions of the building at the floor level excluding plinth offsets. Courtyard, open areas, balconies and cantilever projections are not included in the plinth area.