Question

In a rigid pavement slab of length of 5 m, thickness 20 cm, with coefficient of subgrade restraint as 1.5, the frictional stress developed is_____
(Unit weight of concrete = 2400 kg/cum)

• A. 1.8 kg/sq.cm
• B. 0.9 kg/sq.cm
• C. 1.35 kg/sq.cm
• D. 0.45 kg/sq.cm

Answer 1

The correct option is B 0.9 kg/sq.cm

Frictional stress developed (in kg/sq.cm)
$=\frac{\gamma LF}{2\times {10}^4}$

Where,
$\gamma =\text{unit of concrete in}kg/m^3$
$=2400kg/m^3$
$\text{L = length of slab in 'm'}$
$=5m$
$\text{F = coefficient of subgrade restraint}$
$=1.5$
Frictional stress developed,
$=\frac{2400\times 5\times 1.5}{2\times {10}^4}$
$=0.9kg/sq.cm$