advertisement

Register Number SATHYABAMA UNIVERSITY (Established under section 3 of UGC Act,1956) Course & Branch :B.E - P-CIVIL Max. Marks:80 Title of the Paper :Reinforced Concrete Structures - II Sub. Code :620PT501(2007-08-09-10) Time : 3 Hours Date :03/05/2012 Session :FN ______________________________________________________________________________________________________________________ 1. PART - A (10 x 2 = 20) Answer ALL the Questions How bending action of a circular slab differs from that of rectangular slabs? 2. State any two limitations of direct design method of flat slab. 3. List the modes of failure of a retaining wall. 4. What is the significance of base key in retaining wall? How it is provided? 5. What are the different types of joints in water tanks? 6. Why the columns of elevated tanks braced? 7. Distinguish between bunkers and silos. 8. What are the assumptions made in Janssen’s theory of silos? 9. What are the different types of stairs? 10. Explain the distribution of loading on stairs. PART – B Answer All the Questions (5 x 12 = 60) 11. A circular room has 5m diameter from inside. Design a circular roof slab for the room to carry a superimposed load of 3800 N/m2. Assume that the slab is simply supported at the edges. Use M15 mix and HYSD bars. (or) 12. Design an interior panel of a flat slab having equal panels of 6m x 6m. The panels have drops of 3m x 3m size. The depth of the drop is 250mm and that of slab is 200mm. The internal columns are 500 mm diameter and the column head is 1000 mm in diameter. The storey height above and below the slab is 4m. The loading is as follows: (a) Dead load: self weight + 2.7kN/m2 for floor finish and partition walls (b) Live load: 4kN/m2. 13. Design the stem, heel, toe and key of a retaining wall to retain the earth 4m high. The top surface is horizontal behind the wall but subjected to a surcharge of 17kN/m2. The soil behind the wall is a well drained medium dense sand with following properties: (a) unit weight = 17kN/m3 (b) Angle of internal friction = 30o The material under the wall base is same as above with SBC of 150kN/m2. The coefficient of friction between base and the soil is 0.55. Design the wall using M20 grade concrete and Fe415 steel. (or) 14. Design a Counterfort retaining wall to retain 7m high embankment above ground level. The foundation is to be taken 1m deep where the SBC of the soil is 180kN/m2. The top of the earth retained is horizontal, and soil weighs 18 kN/m3 with angle of internal friction = 30o. Coefficient of friction between concrete and soil may be taken as 0.5. Check the stability of the wall and find the pressure distribution only. 15. An open rectangular tank 4m x 6m x 3m deep rests on firm ground. Design the tank. Use M20 concrete and Fe 415 steel. (or) 16. Design a wall of a rectangular water tank for a direct force of 60 kN/m and bending moment of 40kNm/m, if tension is on liquid face. The materials are M20 grade concrete and HYSD reinforcement of grade Fe415. 17. Design the side walls and hopper bottom of a 3m x 3m square bunker of capacity 3 Tonnes to store coal using M20 concrete and Fe415 steel. Given unit weight of coal = 9 kN/m3, angle of repose of coal = 30o. (or) 18. Compare and comment on the horizontal pressures developed at 5m intervals in a cement silo of internal diameter 10 m and height 30 m using Janssen and Airy’s theories. Take density of cement = 15.2 kN/m3, Coefficient of friction between concrete and cement ' 0.554 , Coefficient of friction between wall & material 0.316 , Angle of repose of cement 17.5o , Ratio of horizontal to vertical pressure k 0.54 . 19. Design a dog-legged stair for a building in which the vertical distance between floors is 3.6 m. The stair hall measures 2.5m x 5m. The live load may be taken as 2500 N/m2. Use M15 concrete and Fe 415 steel. (or) 20. Figure shows a general arrangement of a staircase of a building. The risers are 150 mm and the treads are 250mm. Design the staircase for a live load of 3000 N/m2. The width of the stair is 1.5 m and the width of the wall is 400 mm. Take c cbc 5N / mm2 and t st 140N / mm2 and m = 18. Adopt unit weight of concrete as 2400 N/m3.