The loading beam, shear force and bending moment diagrams are given below.

Find the value of 'y' (contraflexture point) from point B.

Explanation:

Point of contraflexure

• In a bending beam, it is a location where the bending moment is zero (changes its sign).
• In a bending moment diagram, it is the point at which the bending moment curve intersects with the zero line.

Calculation:

Bending moment diagram is shown above and the values are tabulated below:

M_A = 0

MB = -(2 x 1 ) x 0. 5 = -1 kN-m

MC = 1 x 2 = + 2 kN-m

MD = 0

Point of contraflexure 

Let P be the point of contraflexure at a distance y from the support B. From the geometry of the figure between B and C, we find that 

\(\frac{y}{1}=\frac{1-y}{2}\)

\(2y = 1-y\)

\(3y=1\)

\(y=\frac{1}{3}=0.33 m\)