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Course of The First World War - Eastern War Front

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For a pre-tensioned beam, Young's Modulus of steel and concrete are 200 GPa and 35.35 GPa, respectively, If the ultimate shrinkage strain and Ultimate Creep Coefficient are 200 microns and 1.6, respectively, what is the level of sustained stress in concrete at the level of 'steel' if the loss due to creep is three times the loss due to shrinkage?

A

9 MPa

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B

13 MPa

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C

11 MPa

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D

15 MPa

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Solution

The correct option is B 13 MPa
$∵$ Shrinkage loss $= \in_{s c} E_{s}$
Creep loss $= m ϕ f_{c}$
$= (\frac{200}{35.35}) \times 1.6 \times f_{c} = 3 \times \in_{s c} \times E_{s} \Rightarrow f_{y} = 13 M P a$

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