Table of Contents

## ANNA UNIVERSITY B.ARCH ,

## DESIGN OF STRUCTURES – III,VI SEMESTER

**PART A (10 x 2 = 20)**

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### ANSWER ALL QUESTIONS

1.Define a continuous beam.2

2.List out the types of staircases based on Geometry.

3.What are the different failures occur in Retaining wall?

4.Explain the functions of the transverse reinforcement in a reinforced concrete column?

5.Under what circumstances a trapezoidal shape preferred to a rectangular shape for columns combined footing?

6.What is the purpose of a shear key? Describe its action.

7.What are the soil characteristics that govern the design of foundation?

8.What are the criteria for the diameter, number and percentage of reinforcement for the longitudinal bars in reinforced concrete rectangular columns?

9.State the limitations for calculating the bending moments and shear forces for continuous beams using the coefficients recommended in IS:456 – 2000 for plain and reinforced concrete.

10.What is the effective span of stairs with 2.5m going and supported by the landing slabs of 1.5m in the direction of the flight. The landing slabs span perpendicular to the flight at top and bottom.

**PART – B (5x 16 = 80)**

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11. A doglegged staircase for a residential building in which the vertical distance between floor is 3.30m. The stair hall measures 2.50m x 4.50m with 12.5mm ceiling finish. The live load on the stair may be taken as 3.0 kN/m^{2}. Design the stair using Limit State Method.

12. a. Design a axially loaded tied square column 450mm x 450mm pinned at both

ends with an unsupported length of 3m carrying a factored load of 2000 kN. Use State Method.

Or

b.A reinforced circular column is to carry a factored load of 2300kN. The diameter of column is 600mm and effective length of column is 3.60m. The column should have a lateral reinforcement in the form of spiral. Design the column using Limit State Method.

13. a. A floor systems for an office consists of slabs over continuous beams ABC of constant cross sections with AB = 8 mts and BC = 6mts, spaced at 5mts intervals at A,B & C on columns 300mm X 300 mm in size. If the slab that is chosen as 175 mm, Design the beam at mid span of AB and at support B assume a practical width for the beam fy=415n/mm^{2 }, fck = 20 n/mm^{2}.

Or

b Design a simply supported slab to cover the hall with internal dimensions 4.0m x 6.0 m. The slab is supported and on a masonry walls 230 mm thick assume a live load of 3 kn/m^{2 }and a finish load of 1 kn/m^{2}. Use M 20 concrete and Fe 415 steel and finish the slab corners are free to lift up.

14. a. Design an isolated footing for an R.C. column 300 x 300mm to carry an axial load of 600KM. Use M20 concrete, Fe415 steel and working stress method. Assume safe bearing capacity of soil as 200KN/SQM

OR

b.Design a combined rectangular footing for the following data:

Two square columns of size 400mm each carry loads of 600kN and 1200kN. The footing is not to project more than 0.4m beyond the center of gravity of the 600kN. Column. The distance between the centers of the column is 3m. The safe bearing capacity of soil is 400kN/m^{2}. Use M20 concrete and Fe415 steel. Using Working stress theory.

15. a.Design the stem of a cantilever type retaining wall with following data:The height of soil to be retained above the ground level is 4m and depth of foundation 1m. Unit weight of soil is 18 kN/m^{2} and safe bearing capacity of soil is 200kN/m^{2}. Angle of repose of soil is 30^{o} and angle of surcharge is 15^{o}.The thickness of the slab is 400mm. Use Working stress theory.

Or

b. A cantilever retaining wall has a 5.50m stem. It retains earth level with its top.The soil weighs 19kN per cubic meter and ahs an angle of repose of soil is 30^{o}. The safe bearing capacity of soil is 200kN/m^{2}. The coefficient of frictionbetween the base slab and the soil is 0.6. Design the base slab using Working stress theory.

Where can i find answers for this questions ??