Materials that show non-linear behavior or possess inelasticity such as concrete need 0.2% offset to determine its yield point. When materials have identical yield points, this method becomes handy.

Figure-2: 0.2% Proof Stress

First, the initial gradient of the stress-strain curve is considered. Then, moving to the point 0.2% of strain which lays in the x-axis a line is drawn parallelly to the initial gradient. This line intersects at a certain point in the curve called approximate yield point from where the 0.2% proof stress is acquired. This method is the Pre-step stress method of finding out stress.