Physical significance of strain

Hi All,

I would like to know about physical significance of Strain. How
it determines failure of structure?

Say for example Compressive strain of concrete being 0.002.
Does it means that if (any) concrete member of original length 100mm deforms 2
mm (when compressed) will fail? Since Strain in this case will be (2/100) =
0.02?

Request you to help me to understand concept of strain.

Thankyou,

Amit