Which statement is correct for design of beams.

[A] The neutral axis passes through the centroid of the beam section when material follows Hooke’s law.

[B] The beam section is subjected tolongitudinal force.

Explanation:

Beam:

• A beam is a horizontal structural element that is capable of withstanding transverse load primarily by resisting bending.
• The bending force induced into the material of the beam as a result of the external loads, own weight, and external reactions to these loads is called a bending moment.
• If the section is symmetric, isotropic, and the material follows Hook's law then the neutral axis passes through the centroid of the beam section.
• All fibers on one side of the neutral axis are in a state of tension, while those on the opposite side are in compression.
• At the neutral axis, the bending stresses will be always zero.

Since statement [A] is true and [B] is false. Hence option (4) is correct.