The GATE Grind

GATE 2016 CE (CE2) – Question 31

Highway Pavements · Design of flexible and rigid pavements · 1 mark · Multiple choice

In the context of the IRC 58-2011 guidelines for rigid pavement design, consider the following pair of statements. I: Radius of relative stiffness is directly related to modulus of elasticity of concrete and inversely related to Poisson's ratio II: Radius of relative stiffness is directly related to thickness of slab and modulus of subgrade reaction. Which one of the following combinations is correct?

  1. I: True; II: True
  2. I: False; II: False
  3. I: True; II: False
  4. I: False; II: True

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Correct answer: (B) I: False; II: False

Explanation

Westergaard radius is l=[Eh³/(12k(1−μ²))]^(1/4). It increases with E and h, decreases with subgrade reaction k, and increases rather than decreases with positive Poisson ratio μ. Statement I has the wrong μ trend and statement II the wrong k trend. Hence **both false, B**.