Question

When a specimen of M25 concrete is loaded to a stress level of 12.5 MPa, a strain of $500\times {10}^{-6}$ is recorded. If this load is allowed to stand for a long time, the strain increases to $1000\times {10}^{-6}$. In accordance with provisions of IS: 456-2000, considering the long-term effects, the effective modulus of elasticity of the concrete (in MPa) is _______.

• A. 12500

Answer 1

The correct option is A 12500
Short term strain $=500\times {10}^{-6}$
Long term strain $=1000\times {10}^{-6}$

So, creep coefficient,

$\theta =\frac{(1000-500)\times {10}^{-6}}{500\times {10}^{-6}}$

$\theta =1$

Long-term effective modulus

$=\frac{E_s}{1+\theta }=\frac{5000\sqrt{25}}{1+1}$

$=12500N/m{m}^2=12500MPa$

$or{E}_{cc}=\frac{Stress}{Longtermstrain}$

$=\frac{12.5}{1000\times {10}^{-6}}=12500MPa$