v.senthil me two marks q&a unit i ... · as a starting point for levelling. reduced level:...

V.SENTHIL ME www.chennaituitions.in

of 26

TWO MARKS Q&A

UNIT I SURVEYING AND CIVIL ENGINEERING MATERIALS

SURVEYING AND CIVIL ENGINEERING MATERIALS 15 Surveying: Objects – types – classification – principles – measurements of distances – angles – levelling – determination of areas – illustrative examples. Civil Engineering Materials: Bricks – stones – sand – cement – concrete– steel sections. OBJECTS – TYPES – CLASSIFICATION – PRINCIPLES – MEASUREMENTS

OF DISTANCES

1. What is surveying? • Surveying is defined as the process of measuring horizontal distances, vertical

distances and included angles in order to determine the location of points on, above or below the earth surface. Note: The term surveying is generally related to the representation of surface features in a horizontal plane. The process of determining the relative heights in the vertical plane is referred to as levelling.

2. What are the objectives of surveying? • The data obtained by surveying are used to prepare the plan or map showing the

ground features. • Surveying is used to determine the relative heights of objects/points in a vertical

plane. • It is used to fix control points and thus to establish the boundaries. • Setting out of any engineering work like buildings, roads, railway tracks, bridges

and dams involves surveying.

3. What is the difference between a plan and a map? Map is a representation of a large area to a small scale. Example: Map of India, Map of Tamil Nadu. Plan is a representation of a relatively small area to a small scale. Example: Plan of a building.

4. What are the two types of surveying?

® Plane surveying ® Geodetic surveying

5. Differentiate between Plane surveying and Geodetic surveying. Plane surveying is a type of survey in which the surface of the earth is assumed to be plane neglecting the effect of curvature of earth's surface: where as geodetic

http://www.chennaituitions.in


of 26

surveying is the type of survey in which the curvature of the earth is taken into account.

6. What are the different types of surveying based on discipline of survey ?

• Engineering survey • geological survey, • mine survey, • military survey and • archaeological survey.

7. What are the different types of surveying based on instruments?

® Chain surveying © Compass surveying ® Plane table surveying ® Theodolite surveying. ® Tacheometric surveying

8. Names the two principles of surveying • Any surveying work should be carried out from whole to part. • New points should be fixed by at least two independent measurements.

9. What are the various instruments for chain surveying? ® Chain or tape ® Arrows ® pegs ® Ranging road ® Offset rods ® Plumb bob ® Cross-Staff.

10. What is Chain Surveying? The method of measuring a distance with a chain or tape is called chaining. In chain surveying, the area is divided into a network of triangles. No angular measurements are taken. Chain surveying is suitable when the area to be surveyed is small, fairly level and open and has simple details.

11. What is Main survey station? It is defined as the beginning point or end point of a chain line.

12. How the surveying is classified? □ Based on purpose. □ Based on the instruments used



of 26

13. What is the purpose of Chain Chains are used to measure horizontal distances. The length of a link is the distance between the centers of two consecutive middle rings, while the length of the chain is measured from the outside of one handle to the outside of the other handle.

14. List out the purpose of Arrows. Arrows or marking pins are made of out steel wire, and generally, 10 arrows supplied with a chain. An arrow is inserted into the ground after every chain length measured on the ground.

15. What is the purpose of Pegs Wooden pegs are used to mark the positions of the stations or terminal points of a survey line. They are made of stout timber generally 2.5 cm or 3 cm square and 15cm long, tapered at the end.

16. What are the various terms used in surveying? ® Survey station ® Survey lines ® Base Line ® Check Lines ® Tie Lines

17. What are the accessories used in chain surveying? ® Metric chain © Chain pins © Pegs © Measuring tape © Ranging rod © Offset rod.

18. What are the important operations performed in chain surveying? Ranging, Chaining and Offsetting

19. State the advantages and disadvantages of chain survey. Advantages: □ Simple to execute. □ Suitable for short distances □ Suitable for rough area. Disadvantages: □ Not suitable in hilly area. □ Less accurate. □ Difficult to handle.

20. State the principle of chain triangulation. The principle of chain survey or chain triangulation, as is sometimes called, is to provide a skeleton or frame work consisting of a number of connected triangles, as triangle is the only simple figure that can be plotted from the lengths of its sides measured in the field.



of 26

21. Define 'ranging' of a line. The process of establishing intermediate points in measuring a long survey line is known as "Ranging". Ranging a straight line means, fixing a series of pegs or other marks such that they all lie on a straight line.

22. Name the two types of compass. ® Prismatic compass © Surveyor's compass

23. List out the main components of prismatic compass. © Magnetic needle ® Circular ring or compass card ® Pivot © Tripod

24. What is compass surveying? Compass survey is a method of measuring angles in order to determine the angles included between the adjacent lines. Prismatic compass is the instrument used in compass survey.

25. Define Line of Collimation. It is the line passing through the intersection of the horizontal and vertical cross hairs and the optical centre of the object gives and its continuation. It is also called as Line of sight.

26. Distinguish between perpendicular and oblique offsets. The lateral measurement taken from an object to the chain line is known as an offset. Offsets which are not perpendicular to the chain line is called oblique offset.

LEVELLING

27. What is meant by levelling?

Levelling is the process of determining the elevations or relative height of various points on the surface of the earth. This essentially reflects the position of points in a vertical plane.

28. Define Base line & Check line. Base line: It is the longest of the main survey lines. This line is the main reference line for fixing the positions of various stations and also to fix the direction of other lines. Check line: A check line is used in the field in order to check the accuracy of the measurement made.

29. What are the instruments used for levelling? ® Dumpy levels ® Levelling staff



of 26

30. What are the objects of levelling? The following are the main objects or uses of levelling. Q To layout grades. □ To determine the relative heights of different points on the surface of the earth. □ To find the profile of roads, railways, canals etc. iv. To get the contours of an area for future planning and designing etc.

31. What are bench marks and reduced levels. Bench Marks (B.M.): It is fixed point of reference of known elevation. This is used as a starting point for levelling. Reduced Level: Reduced level of a point is its height above or below the datum.

32. State the accuracy to which a reading can be taken on a levelling staff Accuracy of a reading staff is 5 mm (or) 0.005 m.

33. What is the use of plumb-bob? Plumb-bob is used to check the verticality.

34. What is a theodolite? Name the types. Theodolite is an intricate instrument used mainly for accurate measurements of horizontal and vertical angles. It is the most precise instrument available for angular measurements. Theodolites may be classified as transit or non-transit theodolite and also classified as vernier theodolite or micrometer theodolite.

35. Name the methods for calculating reduced levels. □ Rise and Fall method. □ Height of collimation method

36. What is a tacheometer? Tacheometer is nothing but a transit theodolite filled with a stadia diaphragm and an analatic lens. A level can also be used-as a tacheometer but only horizontal sights can be observed.

37. What is centering? Centering is the process of keeping the instrument exactly over the station. Ordinary prismatic compass is not provided with fine centering device as is generally fitted to engineer's theodolite.

38. Define traversing. Traversing is one in which a number of connected survey lines form frame work, and the directions and lengths of the survey line are measured with the help of a compass and a chain respectively.

ANGLES



of 26

39. Distinguish between True Meridian and Magnetic Meridian. The line of intersection of the plane passing through a point and the geographical north and south poles with the surface of the earth is called the, True Meridian of that point. Magnetic Meridian at a point is the direction indicated by a freely floating and balanced magnetic needle at that point, free from all other attractive forces.

40. Define bearing of a line. Distinguish between true bearing and magnetic bearing.

Bearing of a survey line is the horizontal angle made by the line with reference to a meridian. It is measured in the clockwise direction. True bearing of a line is the angle made by the line with the true north or geographic north. It is always measured in the clockwise direction with a measuring range of 0° to 360°. Magnetic bearing of a line is the angle made by the line with the magnetic north. It is always measured in the clockwise direction with a measuring range of 0° to 360°.

41. Distinguish between whole circle bearing and reduced bearing. The bearing of a line measured clockwise from the north pole towards the line is known as the whole circle bearing (W.C.B.) and may have a value 0° to 360°. The W.C.B. of a line is obtained by prismatic compass. The bearing of a line measured clockwise or anticlockwise from North or South pole towards the East or West is known as the quadrantal bearing (Q.B.). It consists of four quadrants NE, SE, SW and NW. The bearing may have a value between 0° to 90°. The Q.B. of a line is obtained by Surveyer's compass.

42. What is meant by Local Attraction? The magnetic needle of the prismatic compass is disturbed by the presence of magnetic iron ore, steel structures, rails, electric cables carrying current, (amp posts etc. near the survey station. The needle will not point to the correct magnetic North in such disturbed conditions. Such a disturbances is called 'local attraction'.

43. Define fore bearing and back bearing. Bearing of a line measured in the direction of progress of survey is called the fore bearing. Bearing of a line measured in the reverse direction of the survey is called the back bearing. The angle difference between the fore-bearing and back-bearing is 180°.

44. Convert the following Reduced bearings to whole circle bearings (i) N 42° W (ii) S 39° 36' E

i) Whole circle bearing of N 43° W is 318° ii) Whole circle bearing of S 39° 36' E is 140° 24'

45. Convert the following W.C.B. to Quadrantal bearing: (i) 165°37' (ii) 281° 45' i. Quadrantal Bearing (or) Reduced bearing = S 14° 23'E ii. Reduced (or) Quadrantal bearing = N78°15'W



of 26

DETERMINATION OF AREAS 46. List out the general methods for calculating areas.

By computations based directly on field measurement:- ® By dividing the area into a number of triangles. © By offsets to base line.

47. What are the various rules followed for determining areas from offsets to a baseline? ® Trapezoidal rule ® Simpson's rule ® Mid - Ordinate rule ® Average -ordinate rule

48. What is Trapezoidal rule? Here the base line is divided into equal parts and ordinates are drawn. The figures between the ordinates, base line and irregular boundary are considered as trapezoids.

49. What is Simpson's rule? In this rule, the boundaries between the ends of ordinates are assumed as an arc of a parabola and it is sometimes known as parabolic rule. This rule is applicable only when the number of ordinates is odd.

50. Compare Traoezoidal rule and Simoson's rule.

ENGINEERING MATERIALS 51. List out important physical properties considered for civil engineering/ building

materials © Density © Bulk Density © Water Absorption © Density Index © Specific Weight © Water Permeability © Specific Gravity © True or absolute specific gravity © Void Ratio © Hygroscopicity

52. What do you mean by Porosity



of 26

It is the degree to which volume of the material of the material is interspersed with pores. It is expressed as a ratio of the volume of pores to that of the specimen.

53. What do you mean by Hygroscopicity It is the property of a material to absorb water vapour from air. It is influenced by air-temperature and relative humidity; pores - their types, number and size, and by the nature of substance involved.

54. List out important mechanical properties considered for civil engineering / building materials

© Compressive Strength ® Tensile Strength ® Bending Strength ® Impact ® Hardness © Elasticity © Plasticity © Abrasion resistance

BRICKS

55. What is standard size of brick?

The standard size of brick as per BIS code is 190mm x 90mm x 90mm with mortar thickness of 10 mm. The average weight of a brick is about 3 to 3.5 kg.

56. What are the four distinct operations of Brick manufacturing? The following are the four processes involved in the manufacture of Bricks. □ Preparation of clay □ Moulding of bricks □ Drying of bricks □ Burning and annealing of bricks

57. What are the components of good brick earth? ® Alumina © Silica ® Lime ® Oxide of iron ® Magnesia

58. How are bricks classified? ® First class bricks © Second class bricks ® Third class bricks © Over burnt bricks ® Under burnt bricks

59. What is a 'frog' in a brick? A 'frog' is a depression of about 10 to 20 mm provided on one side of a brick from the mould during moulding. The frog serves two purposes, viz., □ It indicates the trade name of the manufacturer



of 26

□ It affords a key for mortar when a successive brick is placed over it.

60. What is perforated brick? These brick contain cylindrical holes throughout their thickness. They are light in weight. Heat insulation capacity of these bricks is more but sound insulation capacity is low.

STONES 61. Give some examples for different types of rocks.

® Igneous rocks: Granite, Basalt ® Sedimentary rocks:. Sandstone, Limestone © Metamorphic rocks: Gneiss, Quartzite

62. Match the following rocks: Igneous, Sedimentary, Metamorphic -Marble, Granite, Shale.

Igneous - Granite Sedimentary - Shale Metamorphic - Marble

63. What are the uses of stones in building construction? Stones are used in building construction for □ Foundations □ Walls,Columns □ Arches and lintels □ Roofs □ Floors

64. What is meant by quarrying? The extraction of stones from rocks is known as quarrying, and the locations where stones are extracted and reduced to the required sizes are called quarries.

65. What is Dressing of stones? The process of making quarried stone into a definite and regular shape is known as Dressing of stones.

66. What is the crushing strength for a good stone? Crushing strength should be greater than l00N/mm2 for Igneous rocks, Metamorphic Rocks have crushing strength equal to 100N/ mm2, but sedimentary rocks have low crushing strength.

67. What are the uses of stones? □ For construction of walls, columns and bridge piers. □ For paving work and as road metal. □ For carving and facing works. □ For flooring and lining of walls.

SAND 68. State the Qualities of sand.



of 26

□ Should be of light grey (or) whitish colour, free from salt and organic impurities. □ Should be chemically inert.

69. State the uses of sand. □ Used as Fine aggregate in mortar and concrete. □ Used as Cushion material at the bottom of foundation to distribute the load uniformly to the subsoil. □ Used as a filling material in flooring.

70. Name the three uses of soil as a construction material. Soil is used for the following works as a construction material: □ Construction of earth dam to impound water □ Construction of pavements of roads and airfields □ Land reclamation

CEMENT

71. List out the general properties of cement? □ Cement is one of the binding materials used. □ It provides good strength to the masonry. □ Cement sets when water is introduced to it. □ It can be able to work easily. □ It has good plasticity property. □ It is reasonably resist to weathering effects.

72. List out the engineering properties of cement □ Fineness □ Soundness Setting time □ Compressive strength

73. What are the raw materials used for the manufacture of cement? □ Limestone and silica □ Clay □ Coal. □ Gypsum.

74. List out some varieties of cement. © Ordinary Portland cement ® Rapid hardening cement © Quick setting cement ® High Alumina cement © Acid Resisting Cement © Coloured Cement © White cement © Low heat cement



of 26

75. What is 'clinker? In production of cement, the raw materials are mixed in correct proportions and sent to burning zone. In burning zone the mixed slurry get chemically fused to form hardballs size from 5 mm to 10 mm. These hard balls are known as clinkers.

76. What is the setting time of ordinary Portland cement? ® The initial setting time of OPC should not be less than 30 minutes. ® The final setting time of OPC should not be more than 600 minutes.

77. What is meant by 43 grade cement? 43 grade cement has a cube compressive strength of 43 N/m2 after 28 days curing should take place.

78. What is cement concrete? It is a mixture of cement, sand, crushed rock and water which when placed in skeleton of forms and allowed to cure, becomes hard such as stone. Concrete has attained the status of a major building material in all branches of modern construction.

79. List-out the properties of Cement Concrete. □ It has a high compressive strength. □ It is tree from corrosion and there is no appreciable effect of atmospheric agents on it. □ It forms hard-surface, capable of resisting abrasion, Q It binds rapidly with steel. □ Density of plain concrete is 2400 kg/m3.

CONCRETE

80. What are the types of concrete? ® Plain Cement Concrete ® Reinforced cement concrete © Pre stressed concrete ® Light weight concrete ® No-fines concrete ® Pre-cast concrete ® Fibre reinforced concrete

81. What is meant by 1:2:4 concrete mix? in 1:2:4 concrete mix, the materials are measured by the mass like 1 part of cement, 2 parts of fine aggregate and 4 parts of coarse aggregate.

82. What is RCC? Concrete formed by using cement, coarse and fine aggregates, steel and water is called RCC (Reinforced Cement Concrete).

83. Why are steel rods used in Reinforced Cement Concrete?



of 26

Concrete is good in compression but weak in tension. To take all the tensile forces steel rods are used in concrete.

84. What do you mean by workability of concrete? Workability of concrete is explained as the case with which it can be mixed, transported and placed in position so that the concrete remains homogeneous. Wet concrete are more workable than dry concrete.

85. What is meant by curing of concrete? Curing is the process of keeping the concrete surface damp for a specified period, so that concrete sets properly and attains the desired strength, durability and water proofing characteristics.

STEEL SECTIONS 86. How the steel is classified?

Steel is classified into the following types. © Low carbon steel or mild steel with less than 0.25% carbon. ® Medium carbon or medium hard steel with carbon content between 0.25 % and 0.7 % ® High carbon or hard steel containing carbon from 0.7 % to 1.5 %.

87. What are the market forms of steel © Reinforcing bar © Flat bar © Plate © Angle section © Channel section © T section © I section ® Expanded metal

88. Explain the effect of carbon in steel □ Increase in carbon content increases hardness. □ Increase in carbon content increases the strength properties upto 0.8%. □ Increase in carbon content decreases the ductility. 91. What is Tor steel bar (Rod)? Tor steel rods are twisted or torsion deformed bars. To: steel bars have longitudinal ribs (small projection) in the form of continuous or discontinuous helix and transverse ribs space at nearly uniform intervals.



of 26

UNIT II BUILDING COMPONENTS AND STRUCTURES

Foundations: Types, Bearing capacity – Requirement of good foundations.

Superstructure: Brick masonry – stone masonry – beams – columns – lintels – roofing – flooring – plastering – Mechanics – Internal and external forces – stress – strain – elasticity – Types of Bridges and Dams – Basics of Interior Design and Landscaping.

FOUNDATION -TYPES, BEARING CAPACITY – REQUIREMENT OF GOOD FOUNDATIONS

1. Define safe bearing capacity of soil.

Safe Bearing Capacity of Soil: A load much lower than the ultimate bearing capacity only should be applied on the soil so that perfect safety of the foundation is ensured. This safe load is called the Safe Bearing Capacity of the Soil. Safe Bearing Capacity of Soil is defined as the maximum load per unit area that the soil can carry safely without the risk of failure (collapse). Safe bearing capacity is determined by dividing the ultimate bearing capacity by a suitable Factor of Safely.

2. Distinguish between substructure and superstructure of a building. Substructure is the lowest portion of a building which is usually considered to be located below the ground level. The substructure is nothing but the foundation which is provided to give stability to the building and to distribute the load coming from superstructure. Superstructure is that portion of a building which is constructed above the substructure. It is the major portion of a building which is used by human beings fully.

3. Define foundation.

Foundation is the bottommost part of a structure, below the ground level which transmits the load from superstructure to the underlying soil.

4. What are the different the types of foundation? ® Shallow ® Deep foundation.

5. Distinguish between shallow foundation and deep foundation?



of 26

6. State the essential requirements of a good foundation. • Foundation should be taken sufficiently deep to protect the building against

damages caused by swelling (or) shrinkage of the subsoil. • Foundation base should be rigid to avoid (or) minimise the differential settlement.

7. What are loads acted on foundation?

© Dead load. © Live load. © Wind load

8. When combined footing is used? When the space between two columns is so small that the foundation for individual columns will overlap, combined footing is adopted. Also when the end column is so close to a boundary line that its isolated footing cannot be extended beyond the boundary line, a combined footing is adopted.

9. What is a pile foundation? Piles are slender structural members normally installed by driving by hammer or by any other suitable means. The piles are usually placed in groups to provide foundations for structures. Pile groups may be subjected to vertical loads or horizontal loads or a combination of vertical and horizontal loads.

10. List out the types of piles ® End bearing pile ® Friction Pile ® Compaction pile ® Batter pile © Sheet pile ® Anchor pile

11. Distinguish between pre-cast and cast-in-situ piles. Piles may be cast beforehand outside the site to the required size and length. After they have been cured, they are driven at the required location. Such piles are said to be pre-cast piles. Piles cast at the site itself are known as cast-in-situ piles.

12. When the pile foundation is preferred? • Low bearing capacity of soil. • High water table. • Hard soil strata is available at greater depth.



of 26

13. What are the types of piles used in construction? ® End bearing pile. ® Friction pile. ® Partly bearing and partly friction pile.

14. What are the ways of improving the bearing capacity of soils? • Increasing the depth of foundation • Reducing the air spaces in-the soil mass by compaction • Draining the subsoil water • Grouting the soil mass with cement grout • Confining the soil mass • Injecting chemicals.

BRICK MASONRY

15. Give a list of types of bonds in brick work.

® Stretcher bond © Header bond © English bond © Flemish bond © Raking bond ® Zigzag bond © Garden wall bond

16. What is bond in brickwork? What is its significance? Bond is the systematic arrangement of bricks in each course such that the brick work as a whole is held together both longitudinally and transversely.

17. What is lap in brick work? The horizontal distance between the vertical joints of successive brick course is known as lap.

18. What is Masonry? The art of construction of structures using building units (stone or brick) is known as Masonry. If stones are used it is called stone masonry and if bricks are used it is called Brick masonry.

19. Distinguish between uncoursed and coursed rubble masonry. Uncoursed rubble masonry is built with stones of irregular shape and size as obtained from quarry. In coursed rubble masonry, stones dressed into regular sizes are laid in courses.

20. List the types of floorings. © Stone flooring © Concrete flooring © Granolithic flooring © Terrazo flooring ® Mosaic flooring © Marble flooring



of 26

STONE MASONRY

21. How the stone masonry is classified? Stone masonry is mainly classified into two types: Rubble masonry and Ashlar masonry. © Rubble masonry ® Uncoursed random rubble masonry ® Coursed random rubble masonry ® Uncoursed square rubble masonry ® Coursed square rubble masonry ® Polygonal rubble masonry ® Flint rubble masonry ® Dry rubble masonry © Ashlar Masonry ® Ashlar fine © Ashlar rough tooled ® Ashlar quarry faced ® Ashlar chamfered © Ashlar facing ® Ashlar block-in course

BEAMS – COLUMNS – LINTELS – ROOFING – FLOORING – PLASTERING

22. Write short notes on Beam A beam is a horizontal structural member that carries the roof, floor slab, (or) wall above. It transmits the imposed load including self weight to the walls or columns supporting it.

23. Define Lintel A lintel is a horizontal structural member that is used to bridge small openings left in the walls for doors, windows, ventilators, cupboards, etc.

24. Define plastering. List two types of plasters. Plastering is the method of covering rough and uneven surfaces of various components of a building with a plastic material called mortar. The types are iime plaster, cement plaster and cement-lime plaster.

25. How the beams are classified based on supports? © Cantilever beam © Simply supported beam © Fixed beam © Overhanging beam © Continuous beam

26. What are stirrups? Why are they provided? Stirrups are rectangular or circular rings provided in beams and columns withstand



of 26

the effects due to the shearing force and to keep the main rods in position.

27. 30. What is a column? Column is a structural member used primarily to support compressive stress. Column transfers the load of beam, slab, live load and all dead loads including its own to the foundation. Columns may be of wood, steel, brick, stone, plain concrete or reinforced cement concrete. Reinforced cement concrete columns can take stresses due to bending in addition to compressive stresses.

28. Define slenderness ratio? It is the ratio of the length of column is its least radios gyration.

29. Define Plinth of building A part of the building located between the ground level and the floor level is known as plinth.

30. List out the different types of flooring. © Mud flooring © Brick flooring © Stone flooring © Timber flooring © Cement concrete flooring © Granolithic flooring © Terrazzo flooring © Mosaic flooring © Marble flooring © Tile flooring

31. What is Base course? Base course is the sub-floor which imparts strength and stability to support floor covering and all the super imposed loads.

32. What are the objectives of plastering? □ To provide an even, smooth, regular, clean and durable finished surface and to improve the appearance. □ To provide a base of ground for white washing, colour washing, painting or distempering. □ To preserve and protect the surfaces from atmospheric influences. □ To cover up the use of inferior quality and porous materials and the joints formed in masonry work.

33. Define roof. A roof is defined as the uppermost part of the building, which is constructed to protect the building from weather.

34. State the merits of A.C. sheeting.



of 26

Asbestos Cement (A.C.) roofing sheet can be easily cut to the required size, can be nailed, sawn or screwed. They are light in weight, non-absorptive, strong and tough. Asbestos cement sheets can withstand extreme variation of temperature.

MECHANICS – INTERNAL AND EXTERNAL FORCES – STRESS – STRAIN –

ELASTICITY

35. Define stress and its types? It is the resistance to deformation due to force acting in unit area. Types: Tensile stress, Compressive stress. Shear stress.

36. Define strain and its types? It is a measure of the deformation produced by the application of external load. Types: Tensile strain, compressive strain, Strear strain.

37. What is the value of factor of safety normally adopted? Usual factor of safety adopted is 2 to 3.

38. What is Poisson's ratio? The ratio of lateral strain to the axial strain (in the direction of loading) is a constant known as Poisson's ratio and denoted as 1/m. It varies from 0.25 to 0.3.

39. Define Young's modulus. The ratio of stress to strain within the elastic limit is a constant which is defined by Hook's as Young's modulus or modulus of elasticity (E).

40. Define elastic limit. The limit upto which the body is capable of regaining its shape and size after the removal of load is known as elastic limit.

41. Give the relationship between modulus of elasticity, modulus of rigidity and bulk modulus.

Relation between Young's modulus (E), Modulus of rigidity (G) and Bulk Modulus (K) is given as

Where E = Young's Modulus G = Shear Modulus or Modulus of Rigidity K = Bulk Modulus

TYPES OF BRIDGES

42. What are the basic components of a bridge?



of 26

The various components of a bridge consist of: □ Foundation □ Piers □ Bank connections □ Approaches □ Decks Q Hand rails

43. State the classification of bridges, based on the materials used? ® Masonry bridge. ® R.C.C bridge. ® Pre-stressed concrete bridge. ® Timber bridge. ® Steel bridge.

44. How bridges are classified © According to its function or purpose, as © According to the materials of construction, as © According to Life, as © According to the type of superstructure, as © According to Life the relative position of floor, as © According to alignment, as © According to span length, as

45. State RCC slab bridge? This is the simplest type of RCC bridge and is easy to construct. This consists of simply a slab of uniform thickness laid on two abutments. It is suitable for spans upto 8m.

TYPES OF DAMS

46. What is a dam? A dam is a hydraulic structure constructed across a river or a stream to impound water on one side up to a certain level. It is also constructed for the protection of men and materials during flood by storing the excess flood wastes.

47. What is a buttress dam? A buttress dam is designed to reduce the total volume of concrete by concentrating the materials where stresses are higher. It has relatively thin water supporting face or deck which is supported by buttresses or counter forts that transfer the water load and deck weight to the foundation. It is analysed for stability similar to gravity dam.

48. What are upstream and downstream sides of a dam? The water impounded side is called the upstream side and the other side of the dam is called the downstream side. The area on the upstream side of the dam is the catchment area. The total impounded water on the upstream side is the reservoir.

49. What are various purposes of dams?



of 26

The various purposes of dams are: □ A protection for men and materials at the downstream during floods, □ The stored water is used for irrigation, power generation, and a base for breeding offish. □ A source for water supply and hence a check on the water-bourn diseases. □ As a means for navigation and a place for recreation.

50. Define the following terms in dam; (i) Spillway (ii) Crest (iii) Free Board (iv) Toe (v) Heel

Spillway: Spillway is the waterway provided in the dam or separately for discharging for surplus water that cannot be stored safely in the dam. Crest: The top surface of the dam is called crest of the dam. The crest may be used as roadway. Free Board: The level difference between the top of the darn and the Maximum Water Level is known as Free Board. Toe: The downstream end of the base of the dam is called the toe of the dam. Heel: The upstream end of the base of the dam is known as the heel of the dam.

51. State the circumstances under which each type of dam is suitable. □ Gravity Dam. It is more suitable for steep valleys where earth dams may slip, □ Earth dam. It is more suitable for low bearing capacity of soils and also when the height of the dam is small. □ Arch dam It is suitable where the river has a narrow and deep cross section. Also it is suitable where the height of the dam is very big.

52. What are the types of rigid dam? ® Gravity dam ® Arch dam ® Buttress dam ® Timber and Steel dam

53. What is a drainage gallery? State its function. Drainage or infiltration gallery is an opening provided through the deepest portion of the dam and parallel to the longitudinal axis of the dam. It collects the seepage water and takes the water to a safer place such that the uplift pressure is relieved and the stability of the dam is protected.



of 26

UNIT III POWER PLANT ENGINEERING POWER PLANT ENGINEERING 10 Introduction, Classification of Power Plants – Working principle of steam, Gas, Diesel, Hydro-electric and Nuclear Power plants – Merits and Demerits – Pumps and turbines – working principle of Reciprocating pumps (single acting and double acting) – Centrifugal Pump.

1. Name some sources of energy. Fossil fueis. Nuclear energy. Energy stored in water, Solar Energy, Wind energy, Ocean Energy, Geo - Thermal Energy

2. What is a power plant? A system of equipments which is used to generate mechanical or electrical energy is called power point.

3. What are the different types of power plants? © Steam power plant © Hydel power plant © Nuclear power plant © Gas turbine power plant © Tidal power plant

4. What is a steam power plant? A system of equipments that convert the heat energy into electrical energy is called steam power plant. It is also known as thermal power plant.

5. What is meant by prime-mover? A prime mover is a device that is used to convert energy from any natural source into mechanical energy.

6. What are the four main circuits of a thermal power plant? □ Feed water & Steam flow circuit. □ Coal & ash circuit. □ Air &. gas circuit. □ Cooling water circuit.

7. What is surge tank? In hydro electric power plants, when the load on the generator decreases, the gates



of 26

admitting water must be suddenly closed, due to this sudden decrease in rate of flow pressure in the penstock increases suddenly. This sudden increase in pressure causes hammering action on the penstock. A surge tank is provided to avoid the hammering action.

8. Give the function of condenser in steam power plant. The function of condenser is to condense the steam which has been discharged from the turbine into water. This condensate is feed back into the boiler by a feed pump.

9. What is the purpose of Economiser used in steam power plant? In order to utilize the heat accompanying combustion gases leaving furnace the gases are passed through the heat recovery equipment i.e. Economiser. It is used for heating the feed water by means of flue gas from boiler.

10. Mention the reason for preferring steam power plant to other power plants. □ Less space required. □ Initial cost is low. □ Respond to changing load. □ Continuous power generation.

11. What is meant by pondage? It is defined as a regulating body of water in the form of a relatively small pond provided at the plant. It takes care of the short term fluctuations due to □ Sudden increase or decrease of load on the turbine Sudden changes on the inflow of water. □ Change of water demand by turbines.

12. List the advantages of steam power plant? □ Initial cost is low compared to hydel power plant. □ Installation time required for the plant is less than the hydro power plant. □ The power production not depends on nature's mercy. □ The power plant can be located near load centre. So the transmission cost and transmission losses are considerably reduced.

13. What is hydro electric power plant? A system of equipments which converts the potential energy of water stored in a dam built across the river into electrical energy is called hydro-electric power plant.

14. Write the elements of Hydro - electric power plant. Reservoir Dam, Forebay, Trash rack, Water Way, Draft tube, Surge tank Spill way, power house and equipment

15. What is the function of penstock pipe? Penstock is the waterway to carry water from dam to the power house. Penstock pipes are made up of steel or reinforced concrete.



of 26

16. Why is surge tank located before penstock? Surge tank is located between the penstock and a dam to arrest a sudden rise in water pressure on the penstock.

17. What are the factors to be considered for site selection of a hydro power plant. □ Availability of water. □ Water storage capacity. Q Available water head. □ Accessibility of site. □ Distance from the load centre. □ Type of land site.

18. What is water hammer & how it can be controlled? Water hammer may occur due to sudden closing of water by the governor mechanism, which in turn results in turbulence inside the pipe & the penstock gets damaged. To prevent this surge tank is provided.

19. What is the purpose of draft tubes It is an integral part of reaction turbine draft tube connects the runner exit to tail race in hydro electric power plant.

20. Name the hydraulic turbines used in hydro-electric power plants. ® Pelton wheel ® Francis turbine © Kaplan turbine © Propeller turbine

21. List the advantages of hydro electric power plants. □ Water is the cheapest and reliable source of generation of electrical power because it exists as a free gift of nature. No fuel transportation problem □ No ash disposal problem. □ Quick response to the change of load compared with thermal or nuclear plants □ Maintenance and running costs are low.

22. Write the advantages of Economiser. □ It reduces the loss of heat with flue gas □ It reduces the consumption of fuel G It improves the efficiency of boiler installation

23. Briefly explain nuclear fission & fusion. The uranium & its isotopes like U235 & U238 are used fuel. A slow moving neutron collide with unstable U235 nucleus, gets split into two fragments of nearly equal mass along with 3 fast neutrons & huge amount of heat.

24. Write the essential components in the nuclear Reactor? Fuel, Moderator, Reflector, Coolant, Control rods, shielding.

25. What is the function of Moderator?



of 26

The function of the moderator is to reduce the energy of neutrons evolved during fission from about 2 meV to 0.25 eV in order to maintain the fission chain reaction. By the slowing down of high energy neutrons, the possibility of escape of neutrons is reduced and possibility of absorption of neutrons by fuel to cause further fission is increased.

26. What is meant by cladding? To prevent the contamination of the coolant by fission products the fuel element is covered with a protective coating. This is known as cladding.

27. 2 7. What is the use of regenerator? Regenerator is used to preheat the air entering the combustion chamber and increase the efficiency of the plant.

28. Name any four types of nuclear reactors. ® Boiling Water Reactor (BWR) © Pressurized Water Reactor (PWR) © Fast Breeder Reactor (FBR) ® Heavy Water-cooled Reactor (HWR)

29. Define uncontrolled and controlled chain reaction. When the chain reaction rate will increase exponentially and enormous amount of heat energy will be evolved. Such reaction is known as uncontrolled chain reaction. When only one neutron after every fission is allowed to continue to cause fission reaction, it is known as controlled chain reaction,

30. Name the materials used as moderators. © Heavy water (D2O) ® Graphite © Beryllium

31. How steam turbines are classified? ® Impulse turbine ® Reaction turbine.

32. What is the principle used in a reaction turbine? Reaction turbines are those in which water entering the turbine has got pressure as well as kinetic energy. This means that only a part of available hydraulic energy is transformed into kinetic energy before it enters the turbine under pressure.

33. What is the function of spear in a pelton turbine? Spear is located inside the nozzle to control the amount of water striking the vanes of the runner. It is in conical shape & operated by either hand wheel or automatically in an axial direction. Forward movement of spear reduced the amount of water striking the runner & vice versa for backward movement.

34. What is the purpose of nozzle in turbines? A nozzle is provided at the inlet of the turbine to increase the velocity of water flowing to the turbine.



of 26

35. Explain tidal energy.

Tides on the sea occurs by the gravitational attraction of the sun and moon on the earth. These tides contains large amount of potential energy which is used for the generation of power is called tidal energy.

36. Explain geothermal energy. Heat energy naturally available in the form of steam in some part of earth below the earth surface is called geothermal energy. This heat energy is absorbed by the working medium to produce power. Generally geothermal energy is available in volcanic region.

37. Which type of power plants are used as peak load power plants? Diesel Engine power plant.

38. Write the auxiliary equipments in the diesel power plant? Fuel supply system, Air intake & exhaust system, cooling system, Lubricating system, starting system.

39. What is the function of intercooler in gas turbine power plant? Intercooler is used to reduce the work of the compressor and increase the efficiency.

40. List out the Advantages of Diesel Power Plant □ Plant layout is simple □ It can be located near load centre. □ The plant can be quickly started and can pick up load in very short time □ There are no standby losses. □ Compared to steam power plant using steam turbine, the life of diese! power plant is longer.

41. Define Pump. A pump is a mechanical device used to increase the pressure energy of a liquid. It is used for lifting liquids from a lower level to a higher level. In other words a pump can also be defined as a hydraulic machine which converts mechanical energy into hydraulic energy, ® Centrifugal pump © Reciprocating pump

42. What is the principle of centrifugal pump? The centrifugal pump works on the principle of forced vortex flow. A certain mass of liquid is rotated by an external torque, & pressure head of liquid rises. !t is proportional to the square of tangential velocity of the liquid at that point. Thus at the outlet of the impeller, where radices is more, the rise in pressure head will be more &. the liquid will be discharged at the outlet with a high pressure head. Due to this high pressure head, the liquid can be lifted to a high level.

43. What are the main parts of centrifugal pump?



of 26

□ Impeller □ Casing □ Suction pipe with a foot valve and a strainer □ Delivery pipe.

44. Define suction head and delivery head in case of centrifugal pump. Suction Head (h): It is defined as the vertical height of the centre line of the pump above the liquid surface in the pump from which the liquid is being lifted. It is also called suction lift. Delivery Head (h): It is defined as the vertical height of the liquid surface in the tank to which the liquid is delivered above the centre line of the pump.

45. What is meant by priming? In centrifugal pumps, the delivery valve is closed and the suction pipe, casing and portion of the delivery pipe upto delivery valve are completely filled with the liquid so that no air pocket is left. This is called as priming.

46. Define cavitation. Cavitation is defined as the phenomenon of formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure and the sudden collapsing of these vapour bubbles in a region of higher pressure.

47. What do you mean by reciprocating pump? The mechanical energy is converted into hydraulic energy or pressure energy by sucking the liquid into a cylinder in which a piston is reciprocating, which exerts the thrust on the liquid and increases it hydraulic energy.

48. Differentiate between a single-acting and a double-acting reciprocating pump. In a single-acting reciprocating pump, liquid acts on one side of the piston only. In a double-acting reciprocating pump, the liquid is acting on both sides of the piston. In this pump, the suction and delivery strokes occur simultaneously.


v.senthil me two marks q&a unit i ... · as a starting point for levelling. reduced level:...

Documents