GATE CE 2022: Transportation Engineering & Surveying Quiz #4

In case of governing equations for calculating wheel load stress using Westergaard’s approach, the following statements are made.
Statement-I: Load Stresses are inversely proportional to wheel load.
Statement-II: Modulus of subgrade reaction is useful for load stress calculation.
Which of the following options are correct?

If Rigidity factor < 1 than

A rigid pavement 3 m X 0.2 m has coefficient of relative stiffness 8kg/cm³, Poisson’s ratio 0.15, Coefficient of thermal expansion =10 X 10^-6 /^oC,  and Youngs Modulus = 3 X 10⁴ N/mm².
Bradbury coefficients C_x and C_y are 0.7 & 0.8 respectively. The radius of contact between the road and tyre = 0.15 m, the temperature gradient during night = 15 ^oC.
Find the warping stress (in MPa) at the edge of the rigid pavement.

For a 20 cm thick cement concrete pavement, analysis of stresses gave the following values.
Wheel load stress due to corner loading = 25 kg/cm²
Wheel load stress due to edge loading = 27 kg/cm²
Warping stress at corner region during winter = 7 kg/cm²
Warping stress at edge region during winter = 5 kg/cm²
Warping stress at corner region during summer = 10 kg/cm²
Warping stress at edge region during summer = 8 kg/cm²
Frictional stress at edge region during summer= 5 kg/cm²
Frictional stress during winter = 4 kg/cm²
The most critical stress value for this pavement is ________ kg/cm².

Which of the following statements are true regarding warping stresses in concrete pavements?

i. The pavement warps down at mid day

ii. The pavement warps up at mid day

iii. The pavement warps down at mid night

iv. The pavement warps up at mid night