Statement I: Fibres in the neutral layer of a beam under simple bending is always stressed.
Statement II: The resultant pull or thrust on a transverse section of the beam under pure bending is zero.
Out of following, which option is correct?

Explanation:

• In pure bending, the neutral layer (or axis) is the fiber within the cross-section of a beam that experiences zero longitudinal stress.
• This layer neither stretches nor compresses and hence remains unstressed.
• Under pure bending, there are no shear forces, only bending moments.
• The resultant axial force on a transverse section is zero because the tensile and compressive stresses above and below the neutral axis cancel out.

 Additional Information

Pure Bending:

• Occurs when a beam is subjected to a constant bending moment with no shear force.
• Typical in the middle span of a simply supported beam under two-point loads.

Neutral Axis:

• A horizontal axis within the beam’s cross-section where bending stress is zero.
• Fibers above it are in compression, and those below are in tension.

Internal Equilibrium:

• The compressive and tensile forces due to bending must balance out, hence the net axial force is zero across the section.