Question

Radius of relative stiffness of cement concrete pavement does not depend upon

• A. Modulus of subgrade reaction
• B. Wheel load
• C. Modulus of Elasticity of Concrete
• D. Poisson's ratio of concrete

Hint:

Remember Westergaard's equation: \[ \boxed{ l=\left(\frac{Eh^3}{12k(1-\mu^2)}\right)^{1/4} } \] The radius of relative stiffness depends on slab and foundation properties, not on wheel load.

Answer 1

The Correct Option is B

Concept: The radius of relative stiffness is an important parameter in Westergaard's analysis of rigid pavements. It is given by \[ \boxed{ l=\left(\frac{Eh^3}{12k(1-\mu^2)}\right)^{1/4} } \] where \[ E=\text{Modulus of elasticity of concrete}, \] \[ h=\text{Thickness of slab}, \] \[ k=\text{Modulus of subgrade reaction}, \] \[ \mu=\text{Poisson's ratio of concrete}. \]

Step 1: Identify the influencing parameters. From the above equation, the radius of relative stiffness depends upon
• Modulus of elasticity of concrete.
• Thickness of slab.
• Modulus of subgrade reaction.
• Poisson's ratio of concrete.

Step 2: Determine the parameter not involved. Wheel load does not appear in the expression for radius of relative stiffness. Hence, \[ \boxed{\text{Radius of relative stiffness is independent of wheel load}.} \] Therefore, the correct option is \[ \boxed{(B)\;\text{Wheel load}.} \]