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Jan-29 and 30

A rectangular concrete beam with dimensions of 100mm wide and 300mm deep is prestressed with five 7mm diameter wires located at an eccentricity of 50mm, with an initial stress of 1200 N/mm2 in the wires. The document asks to estimate the final loss of stress in the steel due to creep of the concrete according to the Indian Standard Code method (IS: 1343-2012).

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64 views7 pages

Jan-29 and 30

A rectangular concrete beam with dimensions of 100mm wide and 300mm deep is prestressed with five 7mm diameter wires located at an eccentricity of 50mm, with an initial stress of 1200 N/mm2 in the wires. The document asks to estimate the final loss of stress in the steel due to creep of the concrete according to the Indian Standard Code method (IS: 1343-2012).

Uploaded by

betvwy
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Prestressed Concrete-4

28 January 2021 10:23

A concrete beam of rectangular section 100 mm wide and 300 mm deep is prestressed by five wires of 7
mm diameter located at an eccentricity of 50 mm, the initial stress in the wires being 1200 N/mm2.
Estimate the final loss of stress in steel due to creep of concrete according to the Indian Standard Code
method (IS: 1343-2012).

Prestressed concrete Page 1


IIT-K
A prestressed concrete beam is of post-tensioned where slip in anchorage is 3mm and the length of the beam is
30m. The initial stress in tendon is 1200 MPa and modulus of elasticity of tendon is 2.1x105 MPa. Determine the
percentage loss.

Prestressed concrete Page 2


Prestressed concrete Page 3
A pre-tensioned prestressed concrete beam has size 200mm x 400mm and it is prestressed by a straight tendon
having constant eccentricity of 100mm. The prestress force is 800 kN. The initial tensile stress in tendon is 1100
MPa. Es = 2.1x 105 MPa and Ec = 3.8x 104 MPa. Determine,
(i) Maximum compressive stress in concrete
(ii) Loss due to elastic shortening
(iii) Loss due to creep (creep coefficient = 1.6)
(iv) Loss due to shrinkage in concrete

Prestressed concrete Page 4


A post-tensioned prestressed concrete beam having size 200 x 400 mm is prestressed by parabolic tendons
having eccentricity zero at support and 100mm at the mid span. Es = 2.1x 10 5 MPa and Ec = 3.8x 104 MPa. The
prestress force is 1000 kN. The initial tensile stress in tendon is 1200 MPa. Determine,
(i) Maximum compressive stress in concrete
(ii) Loss due to slip in anchorage where length of beam is 10m and slip is 3mm
(iii) Loss due to shrinkage in concrete (age at transfer is 15 days)
(iv) Loss due to friction (µ = 0.35 and kf= 0.0015)

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