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Total No. of Pages: 2
Register Number: 7404
Name of the Candidate:
POST DIPLOMA/DIPLOMAEXAMINATION – 2012
(CONCERETE TECHNOLOGY AND DESIGN OF CONCRETE STRUCTURES)
(paper – IV)
140.PRESTRESSED CONCRETE
May) (Time: 3 Hours
Maximum: 100 Marks
Answer ONE full question from each Unit.
All questions carry equal marks. (5 × 20 = 100)
Use of IS 1343 and IS 3370 are permitted. Assume suitable data wherever necessary
UNIT - I
1.a) What are the various types of pre stressing? State their important features.
b) What are the advantages of pre stressed concrete constructions?
(OR)
2.Discuss briefly about pre-tensioning systems with neat sketches.
UNIT - II
3.Design for flexure a pre-stressed rectangular beam to carry a UDL of 8 kN/m were simple span of 6 m. Assume fcci = fccf = 16 N/mm2 and no tensile stress. Consider no loss of pre-stress.
(OR)
4.a) Explain the Magnel’s method in the investigator on anchorage zone.
b) Discuss the nature of bond stress in PSC beam and compare with that of RC beam.
UNIT - III
5.A pre-tensioned T section has a flange which is 300 mm wide and 200 mm depth. The rib is 150 mm wide by 350 mm deep. The effective depth of the cross section i 500 mm. Given Ap = 200 mm2, fck = 50 N/mm2 and fp = 1600 N/m n2. Estimate the ultimate moment capacity o the T section.
(OR)
6.a) Discuss the advantages and disadvantages when partial pre-stressing is done.
b) List the advantages in using pre cast pre-stressed units in association with insitu concrete.
UNIT - IV
7.A continuous PSC beam ABC (AB=BC=12 m) has a uniform rectangular cross section with a width of 10 mm and depth of 300 mm. The cable, carrying an effective pre stressing force of 400 kN is parallel to the axis of the beam and located at 100 mm from the soffit. Determine the secondary and resultant moment at the central support B. If the beam supports an imposed load of 1.5 kN m. Calculate the resultant stresses at top and bottom of the beam B. Also locate the resultant line thrust through the beam ABC.
(OR)
8.a) What are the advantages of PSC poles?
b) Explain how a non concordant profile may be transformed into concordant profile.
UNIT - V
9.A non cylinder PSC pipe of internal diameter 1000 mm and thickness of concrete shell
75 mm is required to convey water at a working pressure of 1.5 MPa. The length of each pipe
is 6 m. The maximum direct compressive stresses in concrete are 15 N/mm2 and 2 N/mm2.
The loss ratio is 0.8 Design the circumferential wire winding using 5 mm diameter wire
winding using 5 mm diameter wires stressed to 1000N/mm2.
(OR)
10. a)Explain in detail, the design procedure of cylindrical water tank.
b) What are the merits of prestressed concrete pipes?
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