Question

Long term elastic modulus of M25 Concrete was found to be 15000 MPa. If elastic strain was measured 0.0003 , find the strain in concrete in long term .

• A. 0.0002
• B. 0.0003
• C. 0.0004
• D. 0.0005

Answer 1

The correct option is D 0.0005

$\text{Long term Modulus}=\frac{5000\sqrt{f_{ck}}}{1+\varphi }=15000$
$\Rightarrow \frac{5000\sqrt{25}}{1+\varphi }=15000$

$\Rightarrow 1+\varphi =\frac{5}{3}$

$\varphi =\frac{2}{3}=\frac{\text{creep strain}}{\text{elastic strain}}$

$\text{Creep strain}=\frac{2}{3}\times \text{Elastic strain}$
$=\frac{2}{3}\times 0.0003=0.0002$

Total strain = Elastic strain+ Creep strain = 0.0005