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VTU Civil Engineering (Semester 5)
Design of RCC Structural Elements
June 2015
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) What is meant by normal distribution in statistics and what is the relationship between mean value and characteristics value in such distribution assuming 5% confidence limit?
5 M
1 (b) Derive an expression for limiting values of xo/d ratio from basic for different grades of steel used in RCC beam design. What is their importance?
5 M
1 (c) For a given data of a beam subjected to bending shown that $\dfrac {x_u}{d}=1.2 - \sqrt{ (1.2)^2 - \left ( \dfrac {6.68M_u}{f_{ck} \ bd^2} \right )}\cdot Data: \ b, d \ M_u, \ f_{ck}\ and \ f_y .$
5 M
1 (d) Explain the terms balanced, over-reinforced and under reinforced section in beam subjected to flexure with neat sketches. Which of these should be recommended in deign? And Why?
5 M

2 (a) Determine the flexural steel reinforcement at mid span for a simply supported beam of effective span of 5.25m. The characteristic dead and live loads shall be 15kN/m and 20 kN/m respectively. The cross sectional dimensions are width is 300mm and effective depth is 675mm. Adopt M20 grade concrete and Fe415 grade steel.
10 M
2 (b) A RC beam of section 250mm × 500mm overall dimensions is reinforced with 5 bars of 25 mm diameter on tension side and 5 bars of 12mm diameter on compression side with an effective cores of 50mm for both. Determine the ultimate moment of resistance of the section. Adopt M25 grade concrete and Fe415 grade steel.
 d1/d 0.15 0.10 Fe415, fsc 342 N/mm2 353 N/mm2
10 M

3 (a) Determine the ultimate shear strength of the support section of a RC beam with following data: width, b=300mm, effective depth, d=600mm, Ast=4 bars of 25mm&straighphi;, 8mm ϕ 2 legged vertical stirrups at 150mm c/c, 2 bars of 25mm ϕ are bent up at 45° near the support. Adopt M25 grade concrete and Fe415 grade steel.
10 M
3 (b) Determine the ultimate moment of resistance of flanged beam as shown in Fig. Q3(b). Adopt M20 grade concrete and Fe415 grade steel.

10 M

4 A simply supported RC beam supports a service live load of 8kN/m over a clear span of 3m. Support width is 200mm. Adopt M20 grade concrete and Fe415 grade steel. Design the beam for flexure and shea. Check the beam depth for control of deflection using empirical method. Sketch the reinforcement details.
20 M

5 Design a two way slab of 5×7m (clear dimensions) with all four edges discontinuous and corners held down. The slab has a support width of 300mm on all the four edges. The live reinforcement details.
20 M

6 (a) Design a circular pin ended column of 400mm diameter with helical reinforcement, with unsupported length of 4m. The column is to carry a factored axial load of 1500 kN. Adopt M20 grade concrete and Fe415 steel. Sketch the reinforcement details.
10 M
6 (b) ARC column of size 300mm × 400 has an unsupported length of 3m and effective length 3.6m. Determine the longitudinal steel and transverse steel -if the column is subjected to a factored load of Pu=1000 kN and Mu=210 kN-m. Adopt M25 grade concrete and Fe415 grade steel. Assume d'=60mm. Sketch the reinforcement details.
10 M

7 Design an isolated rectangular footing of uniform depth for the column size of 230mm× 300mm supporting an axial service load of 850kN-m. The safe bearing capacity of soil is 150kN/m2. Adopt M20 grade concrete and Fe415 grade steel. Sketch the reinforcement details.
20 M

8 Design a dog legged staircase for a building in which the vertical distance between floors is 3.5m. The stair hall measures 2.1m×5.0m. Take live load 2 kN/m2. The fights are supported on 230mm walls at the ends of outer edges of landing slab, so that it spans in the direction of going. Adop M20 grade concrete and Fe415 grade steel. Sketch the reinforcement details.
20 M

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