POST DIPLOMA/DIPLOMA EXAMINATION 2012

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Nov 26, 2013 (3 years and 8 months ago)

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2

Register Number:






7
404


Name of the Candidate:



P
OST

DIPLOMA
/DIPLOMA

EXAMINATION


20
12

(
CONCERETE TECHNOLOGY

AND DESIGN OF CONCRE
TE
STRUCTURES
)

(PAPER


I
V
)

1
4
0.

PRESTRESSED CONCRETE

May
)








(
Time: 3 Hours

Maximum: 100 Marks


Answer ONE full question from each Unit.


All questions carry equ
al 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 bea
m

to carry a UDL of 8 kN/m were simple
span of 6 m. Assume f
cci

= f
ccf

= 16 N/mm
2

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 20
0 mm depth. The rib is 150
mm wide by 350 mm deep. The effective depth of the cross section
i

500 mm. Given A
p

= 200
mm
2
, f
ck

= 50 N/mm
2

and f
p

= 1600 N/m n
2
. Estimate the ultimate moment capacity o the T
section.


(OR)

6.

a)
Discuss the advantages and dis
advantages 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
a
n 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.


2


(OR)

8.

a)
What are the advantages of PSC poles?


b)
Explain how a non concordant profile may be tran
sformed 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 maximu
m direct compressive stresses in concrete are 1
5 N/mm
2

and 2 N/mm
2
.


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/mm
2
.

(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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