Highway Engineering - Engineering

Q1:

If d is the thickness of a concrete pavement, the equivalent radius b of resisting section for an interior loading, is

A
b = 0.6 + d2 - 0.675 d

B
b = 1.6 + d2 + 0.675 d

C
b = 1.6 + d2 - 3.675 d

D
b = 1.6 + d2 - 0.675 d

ANS:D -

b = 1.6 + d2 - 0.675 d

It should be 1.6a^2 in option D then only it would be correct, also there are various conditions for that like it is possible only in case when a<1.724d. where a is wheel radius.