Mechanical Engineering - Strength of Materials - Discussion

For a fixed beam there always exist points where BM changes sign.

But for an overhanging beam, it is not necessary that always a point of contra flexure occurs.

A continuous beam is the right answer.

It also occurs in simply supported beam when concentrated moment act on centre.

It is a point in the bending moment diagram at which the bending moment changes its sign from negative to positive or vice versa. It occurs mainly in overhanging beam in which there is opposite magnitude moment acting on another side of overhanging part which makes the net moment to change its sign, by virtue of this the point of contraflexure came into picture. But it is not always in overhanging beam it can also occur in simply supported beam and fixed beams.

OHB, because supports not in ends that's why acting at OHB.

Point of contra-flexure can occur in overhanging and fixed beam both, then why overhanging is taken as the correct answer? why not both as correct answer?

Is there any case of point of contraflexure in simply supported or cantilever beam?

C is correct. Other beams may not have point of contraflexure, but overhanging beam always does.

It also occurs in simply supported beams.

Generally, point of contraflexure occurs in overhanging beams. But it also occurs in fixed beams in few cases. If both are mentioned in the ques, we must go with the overhanging one.