Beam Curvature Change Point

A beam's curvature describes how it bends under load. Sagging refers to downward curvature (like a smile), typically associated with a positive bending moment. Hogging refers to upward curvature (like a frown), usually associated with a negative bending moment.

The specific location on a beam where the curvature transitions from one type to the other (sagging to hogging, or hogging to sagging) is a critical point. At this exact point, the bending moment of the beam changes its sign (from positive to negative or vice versa).

Identifying the Point of Contraflexure

This unique point is technically defined as the point of contraflexure. It is also sometimes referred to as the point of inflection.

Analysis of Options:

• Point of Contraflexure: Accurately describes the location where curvature changes from sagging to hogging.
• Centre of Gravity: This point relates to the distribution of mass, not the bending behavior or curvature change.
• Maximum Stress: Maximum stress occurs where the bending moment is maximum, which is not necessarily the same point where the curvature changes direction.
• Maximum Shear Stress: This relates to the shear force distribution, typically found near supports, and is distinct from the point of curvature change.

Therefore, the point on the beam where the curvature changes from sagging to hogging is identified as the point of contraflexure.