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JNTU B.Tech III REINFORCED CONCRETE STRUCTURES DESIGN AND DRAWING Previous Question Paper (November/December - 2017 - R13)

B.Tech | III | III-I | R13 | November/December - 2017

Answer PaperPaper Code: 115ABMaximum Marks: 75Time: 3 hours

Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.

PART - A

125 marks
a
What is meant by modular ratio? Why it is considered to be an unreliable quantity?
2 marks

Answer

The modular ratio is the ratio of the modulus of elasticity of steel to the modulus of elasticity of concrete (m = Es / Ec). It is considered unreliable because concrete is a non-homogeneous, non-linear, and time-dependent material; its modulus of elasticity varies with stress level, age, and creep, making a single constant value an inaccurate representation of actual structural behavior.

b
Why do continuous T beams at supports have to be designed as rectangular beams?
3 marks

Answer

At the supports of a continuous T-beam, the bending moment is negative, causing tension in the top flange and compression in the bottom web. Since the flange is in tension and cannot contribute to the compression zone, the section acts effectively as a rectangular beam with a width equal to the web width.

c
Why is limitation of deflection in a structure called a serviceability condition? Name another serviceability condition commonly used in limit state design.
2 marks

Answer

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d
Explain the terms development length, lap length and anchorage lengths.
3 marks

Answer

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e
What is the function of providing distribution steel in a slab?
2 marks

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f
Explain clearly the difference in the behaviour of one way slab and two way slabs.
3 marks

Answer

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g
What is meant by slenderness ratio of a compression member and what are its implications?
2 marks

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h
Why does code specify limits to the minimum and maximum reinforcement in columns?
3 marks

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i
What are the situations in which combined footings are preferred to isolated footings?
2 marks

Answer

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j
Why is it desirable to eliminate eccentricity in loading on a footing, wherever possible, by means of proper proportioning?
3 marks

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PART - B

2
Determine the moment of resistance of T beam section with the details given below: bw = 200 mm, d = 600 mm, bf = 1500 mm, Df = 120 mm, Ast = 2415 mm^2, fck = 25 MPa, fy=500 MPa.
10 marks

Answer

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OR
3
A rectangular beam width 350mm and effective depth 550mm has a factored shear of 400 kN at a section near the support. The steel at the tension side of the section consists of 4 - 32mm diameter bars which are continued into the support. Assume fck= 20MPa and fy=415 MPa. Design vertical stirrups for the section.
10 marks

Answer

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4
A simply supported reinforced concrete beam of effective span 5.2 m has cross section 300 mm × 450 mm overall depth is reinforced with 3 bars of 20 mm diameter in tension and 2 bars of 12mm diameter in compression. The beam is subjected to a superimposed working load of 25 kN/m. Determine the short term deflection and long term deflection. Adopt M20 grade of concrete and Fe 415 HYSD steel.
10 marks

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OR
510 marks
a
Give the step by step procedure of calculating the crack width of a RC beam according to IS 456 – 2000
5 marks

Answer

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b
Under what situations do the following modes of cracking occur in reinforced concrete beams: (i) flexural cracks, (ii) diagonal tension cracks, (iii) flexural-shear cracks and (iv) splitting cracks?
5 marks

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6
A one-way slab has been designed for a simply supported effective span of 4.6 m with an overall depth of 160 mm and clear cover of 20 mm, M25 concrete and Fe 500 steel. The dead loads are taken as 4.0 kN/m^2 and the live loads as 2.0 kN/m^2. The longitudinal bars are designed as 12 mm dia @ 150 c/c. Verify the adequacy of the thickness provided, a) Applying the limiting span/effective depth ratio; b) Actual calculation of total deflections.
10 marks

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OR
7
Design a continuous RC slab for a hall 5.0 m × 12.5 m. The slab is supported on RCC beams, each 240 mm wide which are monolithic. The ends of the slab are supported on walls, 300 mm wide. Design the slab for a live load of 2 kN/m^2. Assume the weight of floor finishing equal to 1.5 kN/m^2. Adopt M20 concrete and Fe415 grade steel. Use Limit state method.
10 marks

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8
Design a rectangular concrete column to carry an axial load of 1000kN. The actual length of column is 5.80m. The column is restrained at position and direction at its both ends. M20 grade of concrete and Fe 415 HYSD steel bars are to be used. Adopt the permissible stresses in direct compression for concrete and steel as specified in IS:456-2000.
10 marks

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OR
9
Design a bi-axially eccentrically loaded braced rectangular reinforced concrete column deformed in single curvature for the following data: Ultimate axial load Pcu=1000 kN; Ultimate moment in longer direction at bottom Mcux1=110 kN-m and at top Mcux2= 80 kN-m; Ultimate moment in shorter direction at bottom Mcuy1=40 kN-m and at top Mcuy2= 30 kN-m; Size of the column (bxD) = 300 mm × 480 mm; Unsupported length of column lu=5.80m; Effective length in the long direction lex=5.40 m; Effective length in the short direction ley=4.20 m; M20 grade of concrete and Fe 415 HYSD steel bars shall be used
10 marks

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10
A column 450 × 450 mm in size with 8 steel bars of 18mm diameter transfer a dead load of 620kN and a live load of 860 kN to the footing. The bearing capacity of soil is 120 kN/m^2. M20 grade of concrete and Fe 415 HYSD steel bars shall be used. Design a square footing to support the column.
10 marks

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OR
11
The stair with an open well consists of two flights and a span partly crossing at right angles. There are ten steps of rise 160mm and tread 250mm in each flight and six such steps in cross span. The width of the landings and stairs is 1200mm. The landings are supported on the walls at the ends. Design the stair slab. Provide M20 grade of concrete and Fe 415 HYSD steel bars.
10 marks

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This page contains the solved question paper with answers of REINFORCED CONCRETE STRUCTURES DESIGN AND DRAWING from JNTU for B.Tech CE III III-I, November/December - 2017, R13.

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