JNTU
JNTU B.Tech III DESIGN OF REINFORCED CONCRETE STRUCTURES Previous Question Paper (January/February - 2023 - R16)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions. iv) Use of only IS 456 is allowed.
Part A
What is meant by ‘Transformed section’ as used in ‘Reinforced Sections’?
Answer
A transformed section is a hypothetical equivalent section where the steel reinforcement is replaced by an equivalent area of concrete. This is achieved by multiplying the area of steel by the modular ratio (m), allowing the composite member to be analyzed as a homogeneous material section.
What is meant by ‘balanced section’ as per Working Stress method and Limit state method?
Answer
In the Working Stress Method, a balanced section is one where both concrete and steel reach their respective permissible stresses simultaneously. In the Limit State Method, a balanced section is one where the concrete reaches its ultimate compressive strain (0.0035) at the same time the steel reaches its yield strain.
Explain the difference between ‘flexural bond’ and ‘development bond’.
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What is meant by ‘equilibrium torsion’?
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Distinguish between ‘unsupported length’ and ‘effective length’ of a column.
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What are the functions of a lateral ties in the columns?
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When do the eccentric loadings occur on a footing?
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Explain the situations in which the combined footings are preferred to isolated footings.
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What is the difference in behavior between one-way slab and two-way slab?
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What is the basic difference in structural behavior between ‘stair slabs spanning transversely’ and ‘stair slabs spanning longitudinally’?
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Part B
Design and flexural reinforcement for an RC beam of size 300 mm wide and 500 mm deep to resist an ultimate moment of 460 kNm. Assume moderate exposure condition. Use M 30 concrete and Fe 500 grade steel. Adopt Limit State method. Sketch the reinforcement details.
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A hall of internal dimensions 6 m × 18 m has beams spaced at 3 m c/c and a slab of 150 mm thick. The beams are supported by 300 mm thick walls. The super imposed load on the slab is 4 kN / m2. Design an intermediate T – beam for flexure and shear completely. Assume moderate exposure condition. Use M 25 grade concrete and Fe 500 grade steel. Adopt Limit State method. Sketch the reinforcement details.
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Design the torsional reinforcement in a rectangular beam section 350 mm wide and 750 mm deep, subjected to an ultimate twisting moment of 160 kNm, an ultimate hogging bending moment of 250 kNm and an ultimate shear force of 180 kNm. Use M30 concrete and Fe 500 grade steel. Assume moderate exposure condition. Sketch the reinforcement details.
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What are the mechanisms by which bond resistance is developed in reinforced concrete?
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For a reinforced concrete tension member, a 20mm diameter rebar has to be lap spliced with a 25mm diameter rebar. Use M 25 concrete and Fe 500 grade steel. Design a suitable splice.
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Design an axially loaded rectangular column with an unsupported length of 4.3 m. The column is fixed at one end and pinned at the other end. The column has to carry a factored load of 2700 kN. Use M 30 grade concrete and Fe 500 grade steel. Sketch the reinforcement details. Assume moderate exposure condition.
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A column 300 mm × 400 mm has an effective length of 3.6 m. It is subjected to an ultimate load of 1500 kN and an ultimate moment of 260 kNm about its major axis. Determine the longitudinal and transverse reinforcement. Use M40 concrete and Fe 500 grade steel. Assume moderate exposure condition. Sketch the cross-section showing reinforcement details.
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Design a rectangular isolated stepped footing for a column of size 350 mm × 650 mm carrying an axial load of 2800 kN. The S.B.C. of the soil is 350 kN / m2. Use M 30 grade concrete and Fe 500 grade steel. Assume severe exposure condition.
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Design an isolated circular footing for a reinforced concrete circular column 600 mm diameter, subjected to a factored axial load of 1600 kN. The column is reinforced with 8 reinforcing bars of 20 mm diameter. The safe bearing capacity of the soil is 300 kN/m2 at a depth of 1.5 m. Assume M35 grade concrete and Fe 500 grade steel. Sketch the reinforcement details.
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Design a R.C. slab for a room measuring 4 m × 6 m. The slab carries a live load of 3.5 kN/m2. The slab is simply supported at all the four edges with corners free to lift. The width of the supporting walls is 300 mm. Use M 30 grade concrete and Fe 500 grade steel. Sketch the reinforcement details. Assume mild exposure condition.
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A simply supported one-way slab 150 mm thick having an effective span of 4.5 m is reinforced with 10 mm diameter bars spaced at 125 mm c/c at an effective cover of 25 mm. The slab is subjected to a live load of 3 kN/m2 and a surface finish of 1 kN/m2. Use M25 concrete and Fe 500 grade steel. Assume ultimate shrinkage strain = 0.0003 and creep coefficient = 1.6. Estimate the only the long-term deflection.
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