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

GENERAL ENGINEERING CIVIL AND  STRUCTURAL

Total Questions: 50

31. In a levelling survey work, the first staff reading taken to a staff station after shifting the instrument and the last staff reading taken to a staff station before the instrument is shifted are, respectively:

Correct Answer: C. back sight and foresight
Solution:Back sight: The first staff reading taken by the surveyor after the levelling instrument is set up and levelled. B.S. is generally taken on the point of known reduced level as on the benchmark or a change point.

Foresight (FS): The last staff reading was taken before changing the instrument to the other position. It is the staff reading taken on a point whose RL is to determined. This sight is considered as negative and deduced from Height of Instrument to determine RL of the point.

Intermediate sight: All readings taken between back sight and foresight. These are the points whose RL is determined by the methods already mentioned above in FS.

32. What is the mechanical extra widening required for a two-lane pavement of width 7 m on a horizontal curve of radius 250 m, if the longest wheel base of a vehicle expected on the road is 5 m with a design speed of 70 km/h?

Correct Answer: D. 0.100 m
Solution:Radius of the curve, R=250 m
Wheel Base, L=5 m
Design Speed, V = 70 km/hr
Number of traffic lanes, n=2

Extra widening, Wₑ = nl²/2R + V/9.5√R
As here pavement width W =7> , wheel base (5m)
∴ Extra widening, Wₑ = nl²/2R
=2 x (5)²/2 x 250 =1/10 =0.1 m.

33. The Indian Roads Congress (IRC) was founded in the year:

Correct Answer: C. 1934
Solution:The IRC was set up in December, 1934 on the recommendations of the Indian Road Development Committee best known as Jayakar Committee set up by the Govt. of India with the objective of Road Development in India.

34. Saturated unit weight of soil is the ratio of:

Correct Answer: C. bulk unit weight of a soil when it is fully saturated
Solution:When the soil mass is saturated, its bulk unit weight is called the saturated unit weight. Thus, saturated unit weight is the ratio of the total weight of a saturated soil sample to its total volume (v).

35. What is the principle of plane surveying?

Correct Answer: D. Working from whole to part
Solution:Working from whole to part: The second ruling principle of surveying, whether plane or geodetic, is to work from whole to part. It is very essential to establish first a system of control points and to fix them with higher precision. Minor control points can then be established by less precise methods and the details can then be located using these minor control points by running minor traverses etc. The idea of working in this way is to prevent the accumulation of errors and to control and localise minor errors which, otherwise, would expand to greater magnitudes if the reverse process is followed, thus making the work uncontrollable at the end.

36. The following are some of the errors that are associated with a total station survey work. Vertical collimation error, Centering error, Horizontal collimation error, Eccentricity error, Categorize the given errors as those due to temporary adjustments (T) and permanent adjustments (P).

Correct Answer: C. T : Centering error P : Vertical collimation error, Horizontal collimation error, Eccentricity error
Solution:If the fundamental relationship between various axes of the theodolite (horizontal axis, vertical axis, line of sight, line of collimation) are not in order, then the movement of the telescope leads to errors in angular measurement. Hence, all permanent adjustments need a periodical check and maintenance. Temporary adjustments during the field work are also very important to eliminate all possible errors.

Principal lines of a theodolite are: vertical axis, horizontal (trunnion) axis, line of sight (collimation), axis of plate level (bubble) and axis of altitude level (bubble).

37. According to IS 800 : 2007, identify the property which is considered as a mechanical property of structural steel, important in design.

Correct Answer: C. Maximum per cent elongation on a standard gauge length
Solution:The properties of steel required for engineering design may be classified as:

(i) Physical Properties
(ii) Mechanical Properties

(i) Physical Properties: Irrespective of its grade physical properties of steel may be taken as given below:

(a) Unit mass of steel, p = 7850 kg/m³
(b) Modulus of elasticity, E = 2.0 x 10⁵ N/mm²
(c) Poisson's ratio, µ = 0.3.
(d) Modulus of rigidity: G = 0.769 x 10⁵ N/mm²
(e) Coefficient of thermal expansion, α = 12 x 10⁻⁶/°C.

(ii) Mechanical Properties: The following are the important mechanical properties in the design:

(a) Yield stress f.
(b) The tensile or ultimate stress f.
(c) The maximum percentage elongation on a standard gauge length and
(d) Notch toughness.

38. The basis for classification of ordinary Portland cement (OPC) as grade 33, 43 and 53 as per IS 10262 is:

Correct Answer: D. 28 days compressive strength
Solution:Ordinary Portland Cement (OPC) is the most widely used cement in the world for producing concrete, mortar, stucco, and non-specialty grouts. Ordinary Portland Cement has 3 grades based on its strength namely 33, 43 and 53 grade that indicates the compressive strength obtained after 28 days of setting.

39. Select the correct option with regard to the following statements (S1, S2) pertaining to pavements.

S1: Present serviceability index is used for the functional evaluation of pavement surface condition.

S2: Rigid pavements are less affected by temperature variations than flexible pavements.

Correct Answer: C. Statement S1 is true and Statement S2 is false
Solution:Consider the following statements regarding pavements:

(a) Rigid pavements are more suitable than flexible pavements for stage construction.

(b) Rigid pavements are more affected by temperature variations than flexible pavements.

(c) In a flexible pavement, any deformation in the top layers is transferred to under-laid layers; but, in rigid pavements, there is slab or beam action due to which any deformation is only in the top layer of the concrete slab.

The Present Serviceability Index (PSI) is one common evaluator used to describe the functional condition with respect to ride quality. Pavement Condition Index (PCI) is another index commonly used to describe the extent of distress on a pavement section.

40. A Pelton wheel is to be designed for a pitch diameter of 1 m and jet diameter of 0.1 m. The number of buckets on the runner computed by Taygun's formula is:

Correct Answer: A. 20
Solution: