Common Question (Attempt Any Five): (5*5=25)

CIVIL ENGINEERING

PAPER: Structural design 3

Common Question (Attempt any five): (5*5=25)

1. What are the general principles of seismic design

2. What are the guidelines for earthquake resistant design

3. What is the concept of design of box culvert

4. Define pre tensioning & post tensioning method

5. Why there is a need for pre stressing and what are the losses in pre stress

6. What are the forces required for the analysis of steel water tank and transmission towers

Unit- 1

1. Write down the general specifications for ductile detailing in earth quake resistant design as per IS 13920:1993. (12.5)

2. A multi storey rigid jointed plane frame (Special RC moment resisting frame) with number of stories 4 (G+3) with floor height 3.5 m, with a imposed load of 3.5 KN/m2 in seismic zone 4 and type of soil as rocky. Concrete M 20 & Steel Fe 415. Analyse the frame using Response Spectrum method. (12.5)

Unit 2

3. Design a cantilever retaining wall to retain a lever earth fill to 4.5 m above ground level. The surcharge on the earth fill is 15 kN/m2. The angle of repose of soil is 300, unit weight of soil is 16 KN/m3, coefficient of friction between soil and concrete is 0.6 and the safe bearing capacity of soil is 150 KN/m2.use M 20 concrete and Fe 500 steel.

4. Design a counter fort type retaining wall to the following particulars:

a) Height of the wall above the general G.L = 5.5m

b) Safe bearing capacity of soil = 160 KN/m2

c) Angle of repose – 300

d) weight of soil is 16 KN/m3 e) Spacing of counter fort = 3m centres

Use M20 Concrete & Fe 415 Steel (25)

5. Design a underground water tank reservoir 12m X 5m X 2.8m including a free board of 0.3 m. The dry density of soil is 16 KN/m3 and the angle of repose is 30. The outside soil which is 0.3 m below the top of the tank wall may be taken as fully saturated up to its full height. Use M 20 concrete and Fe 415 steel. (25)

Unit -3

6. A rectangular beam 100mm wide by 250mm deep, spanning over 8m is prestressed by straight cable carrying an effective prestressing force of 250 KN located at an eccentricity of 40 mm. The beam supports a live load of 1.2kN/m. Calculate the resultant stress distribution for the central cross section of the beam. Assume density of concrete to be 125 kN/m3. (12.5)

7. A post tensioned prestressed concrete beam is prestressed by 4 tendons of straight cable of 300 mm2 area inch. Calculate the loss of prestress in the steel reinforcement due to elastic shortening if each steel in tensioned to 1600 N/mm2 , if wires are tensioned one by one. The member is not subjected to dead load & live load. (12.5)

Unit-4

8. Design a welded mild steel circular tank with hemispherical bottom of capacity 50000 litres. Also design a suitable staging of pipe columns. The lowest point of tank should be at least 5 m above the ground level the tank is open at top; the soil is type 1, hard. F y = 250 N/mn2. (25)

9. What are the types of transmission line towers? What is meant by tower configuration and what are the loads acting on transmission line tower? (12.5)