Ce2404-Prestressed Concrete Structures

OXFORD COLLEGE OF ENGINEERING DEPARTMENT OF CIVIL ENGINEERING CIAT TEST- II CE2404-PRESTRESSED CONCRETE STRUCTURES Date : 20.09.13

MARKS : 100

PART – A 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

(10x2 = 20)

Time: 3hours

Why is high tensile steel needed for PSC construction? State the advantages of PSC construction? What are the types of prestressing losses? What is the assumption made in pre-stressed section? Explained the eccentric tendon in PSC? What are the different types of flexural failure modes observed in psc beams What is the zone of transmission in end block of psc structures? Write down any two assumptions of strain compatibility method in psc section. What are the functions of water stopper in water tank construction? Differentiate prestressed cylinder and non cylinder pipe.

PART – B

(16X5 = 80)

11. A PSC beam of length 10m is SS at its ends and subjected to a load of 50KN/m, the size of the beam is 500x800mm.it is pre-stress eccentric tendon at the eccentricity of 300mm bottom of the beam with a pre-stress force of 1500KN.find out either extreme stresses at mid span, quarter span and support by (i)stress concept (ii)strength concept 12. A PSC beam of rectangular c/s 120x300mm with support and a udl of 4KN/m which includes the self wt of the beam 6m and concentrically pre-stress by a cable carrying a force of 180KN.and located at an eccentricity of 50mm.determine the Located of the thrust line in the beam and plot its position. 13. The end block of post tensioned psc beam 300mm wide and 300mm deep is subjected to a concentric anchorage force of 800kN by a freyssinet anchorage system of area 1100mm 2. Design and detail the anchorage reinforcement for the end block. 14. The end block of prestressed concrete beam, rectangular in section is 100mm wide and 200mm deep. The prestressing force of 100 kN is transmitted to concrete by a distribution plate, 100 mm wide and 50 mm deep, concentrically located at ends. Calculate the position and magnitude tensile stress on the horizontal section trough the center and edge of the anchor plate. Compute the bursting tension on the horizontal plate. 15. Design a cylindrical prestressed concrete water tank to suit the following data: capacity of tank 3.5x106 liters. Ratio of diameter to height 4. Maximum compressive stress in concrete at transfer not to exceed 14N/mm2 (compression). Minimum compressive stress under working load to be 1 N/mm2.The prestress is to be provided by circumferential winding of 5 mm dia wires at transfer = 1000 N/mm2.Loss ratio = 0.75.Design the walls of the tank and details of circumferential wire winding and vertical cables for the following joint condition at the base: Hinged base (assume co-efficient of friction as 0.5).