Previous Year Question Paper

Engineering Services (Main) Examination, 2024

GSGE-0- CVL Civil Engineering Paper - I

Time Allowed : Three Hours Maximum Marks : 300

Describe how stones are preserved.

What are the advantages and disadvantages of fibre reinforced concrete?

A factory shed of size 40m × 18m is to be constructed at New Delhi with roof trusses. Calculate the nodal wind force on a roof truss of span 18m and central rise of 3m. The spacing of roof truss is 4m, basic wind speed = 50 m/s, K₁ = 1, K₂ = 0.9 (up to 10m ht and category- II), K₃ = 1, K₄ = 1, K_a = 0.9, K_c = 0.9, K_d = 0.9. For wind angle 0°, take Cpe = -1.2 (windward side), Cpe = -0.4 (leeward side). Assume wall opening is less than 5%. Purlins are located at the node points. Show the forces in a sketch of truss for wind angle 0° only.

[Image: please refer to given pdf link for image and diagram]

A simply supported prestressed concrete beam of span 12m and size 300 × 700mm carries uniformly distributed load of 20 kN/m. Suggest a suitable cable profile and the prestressing force so that no tension is developed in the beam. Assume density of concrete to be 24 kN/m³. Maximum eccentricity for the cable to be provided is 200mm.

A metallic rod 6·25m long and 35mm in diameter is subjected to an axial tensile load of 65 kN. Determine the change in dimension and volume of the rod. Assume modulus of elasticity of metal as E = 2·10 × 10⁵ N/mm² and Poisson's ratio = 0·26.

6 (ii) What are the effects of air- entraining admixtures on the properties of concrete? 6

Q2. (a) A circular hollow section of outside diameter 101.6 mm and thickness 4.05 mm is connected to a plate of thickness 16 mm as shown in the figure, by welding of weld size 4 mm. Determine the maximum load P that can be applied for the weld. The hollow section is safe. Assume shop weld to be made. Apply limit state method. Assume E 250 grade of steel. Given f_e = √(f_a + 3q²). Assume partial load factor as 1.5. 20

[Image: please refer to given pdf link for image and diagram]

(b) Discuss the mechanisms that are used to enhance the performance characteristics of the concrete. 20

(c) (i) Two rectangular plates, one of steel and another of brass, each 50 mm wide and 8 mm deep are placed together to form a beam 50 mm wide and 16 mm deep, on two supports (simply supported) 1 m apart, the brass plate being on the top. Determine the maximum load which can be applied at the centre of the beam, if the plates are separate and can bend independently. Maximum allowable stress in steel = 120 N/mm² and in brass = 80 N/mm². Take E_s = 2 × 10⁵ N/mm² and E_b = 8 × 10⁴ N/mm². 10

10

[Image: please refer to given pdf link for image and diagram]

Q3. (a) (i) What is quality management system in concrete construction? 10 (ii) What is cement grout? How does it differ from cement mortar? 10

(b) Design a reinforced concrete isolated square footing for a column of size 500 mm × 500 mm subjected to an axial load of 1500 kN under dead and live load condition. The safe bearing capacity of the soil is 120 kN/m² Apply limit state method of design and use M25 and Fe500. Assume uniform thickness of footing as 600 mm. Nominal cover = 50 mm. No pedestal is to be provided. Given :

[Table: please refer to given pdf link for table]

| 100 A_st / b_d | ≤ 0·15 | 0·25 | 0·50 | 0·75 | 1·00 | 1·25 | 1·50 | 1·75 |
|---|---|---|---|---|---|---|---|---|
| τ_c N/mm² | 0·29 | 0·36 | 0·49 | 0·57 | 0·64 | 0·70 | 0·74 | 0·78 |

Use table 3 of SP - 16.

Show reinforcement details. The column is reinforced with 8 nos. of 20 φ bars. 20

240 250 415 480 500 f y 240 250 415 480 500 f ck 25

[Table: please refer to given pdf link for table]

(c) (i) Draw the influence line diagram for reaction R_A for the continuous beam shown in the figure at 1 m interval. Assume flexural rigidity is constant throughout. Use Muller- Breslau Principle. 10

[Image: please refer to given pdf link for image and diagram]

(ii) Draw the influence line diagram for member ID of the truss shown in the figure. Assume that the load moves along the bottom chord. 10

[Image: please refer to given pdf link for image and diagram]

Q4. (a) (i) A single storey building is idealised as a rigid bar supported by weightless columns as shown in the figure. For dynamic response, using jack, a displacement of 5 mm of the girder was observed for a force of 10 kN. After instantaneous release of this initial displacement, the maximum displacement on the return swing was only 4 mm and the period of displacement cycle was 1·5 sec. Find approximately, the effective weight of the girder, damping factor and damping coefficient. 12

[Image: please refer to given pdf link for image and diagram]

8

(ii) A cantilever beam AB is fixed at B and is supported at A by the bar AC which serves as a yielding prop. Determine the tensile force in the bar if it is extensible, and if it is inextensible. EI is same for the beam and the bar. For the beam, take moment of inertia I = 0.05 m⁴ and for the bar take L = 5 m and area of cross- section A = 1500 mm². (Refer the following figure for loading)

[Image: please refer to given pdf link for image and diagram]

(b) (i) A small maintenance project consisting of jobs given in the following table, with normal time and crash time are given in days.

(I) What is the normal length and its cost?

(II) If the project duration is to be crashed by 2 days, what is the total project cost? 10

Overhead costs are π 2,000 per day.

| Activity | Duration (days) Normal | Duration (days) Crash | Cost (₹) Normal | Cost (₹) Crash |
|---|---|---|---|---|
| 1-2 | 4 | 2 | 4,000 | 12,000 |
| 2-3 | 5 | 2 | 3,000 | 6,000 |
| 2-4 | 7 | 5 | 4,000 | 6,000 |
| 3-4 | 4 | 2 | 8,000 | 12,000 |

(ii) Write a note on resources smoothing and resources levelling. 10

20

(c) Analyse the portal frame shown in the figure by using slope-deflection method. Take EI as constant and draw the bending moment diagram. Supports A and D are fixed.

[Image: please refer to given pdf link for image and diagram]

6 (a) (i) What is the difference between soft wood and hard wood? 6 (ii) What are the different phases of a project? 6 (b) A suspension bridge of 116 m span has three- hinged stiffening girder, and is subjected to two concentrated loads of 250 kN and 340 kN at a distance of 30 m and 58 m respectively from the left support. Determine the shear force and bending moment for the girder at a distance of 35 m from the left end. The supporting cable has a central dip of 12 m. Also determine maximum tension and its slope in the cable. 12 (c) What are the four classes of steel sections as per IS : 800 - 2007 ? Explain with a moment- rotation diagram and a stress diagram. 12 (d) Find the development length for a reinforcement bar of diameter 20 mm under tension and compression embedded in concrete of M30 grade. The design bond stress τ_bd in limit state method for plain bar in tension is 1 - 5 MPa for M30. The grade of reinforcement bars is Fe500. Also find the corresponding anchorage lengths of the bar for 90° bend. 12 (e) The maximum allowable shear stress in a hollow shaft of external diameter equal to twice the internal diameter is 120 N/mm². Determine the diameter of the shaft if it is subjected to a torque of 12 kNm and a bending moment of 5 kNm. 12

(b) A suspension bridge of 116 m span has three- hinged stiffening girder, and is subjected to two concentrated loads of 250 kN and 340 kN at a distance of 30 m and 58 m respectively from the left support. Determine the shear force and bending moment for the girder at a distance of 35 m from the left end. The supporting cable has a central dip of 12 m. Also determine maximum tension and its slope in the cable. 12

Q6. (a) (i) Using the unit load method, determine the horizontal deflection of the free end (Point A) of the frame shown in the figure below. Support D is fixed, C and B are rigid joints. Assume flexural rigidity EI as constant. 10

[Image: please refer to given pdf link for image and diagram]

10

[Image: please refer to given pdf link for image and diagram]

(b) The member A- B- C in a truss consists of two angles ∠ 75 × 75 × 8 back to back on both sides of the gusset of thickness 10 mm. The length of members AB and BC is 1·5 m each. Find the maximum (factored) compressive load carrying capacity of the member A- B- C. Assume E250 grade of steel and all joints are welded. Properties of ∠ 75 × 75 × 8 are:

A = 1140 mm², C_y = C_z = 21·4 mm, I_yy = I_zz = 59 × 10⁴ mm⁴.

[Image: please refer to given pdf link for image and diagram]

20 224 30 211 40 198 50 183 60 168 70 152 80 136 90 121 100 107 110 94·6 120 83·7 130 74·3 140 66·2 150 59·2 160 53·3 170 48·1 180 43·6

(c) The cost of a machine required at the construction site is π 1,20,000 and its salvage value is π 20,000. The expected life of the machine is 5 years only. It is also expected to work 2000 hours in a year. Compute the yearly depreciation for the machine by using the following methods : 20

Straight line method Sinking fund method

Q7. (a) A cylindrical shell of mild steel sheet and 1250mm diameter is to be subjected to an internal pressure of 1·55 MN/mm². If the mild steel yields at 225 MN/m², determine the thickness of the mild steel sheet on the basis of the following theories of failure. Assume a F.O.S. = 3

(i) Maximum principal stress theory (ii) Maximum shear stress theory (iii) Maximum shear strain energy theory

(b) A dog- legged stair is to be constructed in a building resting on beams and columns as shown in the figure. The floor to floor height of the building is 3 m. The cross- sectional dimensions of beams including half landing beams are 250 mm × 400 mm. Intensity of live load is 3 kN/m². Design and detail the reinforcement (with sketches) of a typical flight of the stair, applying 'limit state method' of design. Use M25 and Fe500. Deflection check is not needed. Assume the depth of waist slab as 150 mm.

[Image: please refer to given pdf link for image and diagram]

[Table: please refer to given pdf link for table]

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| Ingredients | Batch Mass (kg) | Specific heat cal/gm/°C | Initial Temperature (°C) |
|---|---|---|---|
| Cement | 860 | -2 | 74 | 4 |
| Sand | 3200 | -2 | 52 | 6·0 |
| Coarse Aggregate | 1498 | 0 | -2 | 34·2 |
| Water | 351 | -1 | 0 | 0 | 1·8 |
| Free Moisture in Sand (3%) | 9·0 | 1·0 | 0 | 26·0 |
| Free Moisture in Coarse Aggregate (1%) | 14·5 | 1·0 | 0 | 4·2 |
| Ice | X | 0·5 | 0 | -4·0 |

If the desired placement temperature is 11°C and concrete gains 4°C after cooling has occurred, find the quantity of ice to be added for the given set of materials.

(ii) What are the causes of accidents in the construction industry? How can they be reduced? 10

Q8. (a) Draw the shear force and bending moment diagrams for the beam loaded, as shown in the figure below. There is an internal hinge at C. Determine the values of maximum bending moment and maximum shearing force. 20

[Image: please refer to given pdf link for image and diagram]

10

(b) (i) A welded plate girder is made of a web 2000 mm deep and 20 mm thick and flange 500 mm wide and 40 mm thick. Design a suitable welded connection between the flange and web. The span of the girder is 30 m (simply supported) and the total load (udl) including its self weight is 160 kN/m. Assume E250 grade of steel. Assume field weld.

(ii) Find the moment of resistance of reinforced concrete beam of size 250 mm × 500 mm. The beam is reinforced with 3 Nos. 20 φ bar at bottom and 2 Nos. 12 φ bar at top. The beam is simply supported and under vertical load. Assume effective cover to bar at the top and the bottom is 50 mm. Use M25 and Fe415. Apply limit state method. Assume the stress strain values of a steel bar from the table.

| Strain | Stress (MPa) |
|---|---|
| 0·00174 | 347·8 |
| 0·00195 | 369·6 |
| 0·00226 | 391·3 |
| 0·00277 | 413·0 |
| 0·00312 | 423·9 |
| 0·00417 | 434·8 |

(c) (i) What is a sheep's foot roller? How does it compact the earth? 10

(ii) Explain the following terms:

Total float Free float Independent float Interfering float

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