Question

A beam is a structural member which is subjected to

• A. Axial tension or compression
• B. Transverse loads and couples
• C. Twisting moment
• D. No load, but its axis should be horizontal and x-section rectangular or circular

Hint:

Remember: Beams resist bending due to transverse loads, columns resist axial loads, and shafts resist torsion.

Answer 1

The Correct Option is B

Step 1: Understanding the concept of a beam.
A beam is a structural member designed primarily to resist loads that act perpendicular to its longitudinal axis. These loads cause bending and shear stresses within the beam. Beams are commonly used in structures such as bridges, buildings, and frames.
Step 2: Analysis of the given options.
(A) Axial tension or compression: This type of loading is mainly associated with columns or tie members, not beams. Hence, this option is incorrect.
(B) Transverse loads and couples: Correct — Beams are subjected to transverse loads (loads acting perpendicular to the axis) and bending moments or couples, which cause bending of the beam.
(C) Twisting moment: Twisting moments primarily act on shafts, not beams, so this option is incorrect.
(D) No load, but its axis should be horizontal and x-section rectangular or circular: This statement does not define the loading condition of a beam and is therefore incorrect.
Step 3: Conclusion.
A beam is mainly subjected to transverse loads and bending moments (couples). Therefore, the correct answer is (B) Transverse loads and couples.

Answer 2

A beam is defined by the type of loading it is designed to carry, as distinct from other structural members like columns (axial loads) or shafts (torsion). Let's check each option.

1. Axial tension or compression: Members loaded purely along their own axis are columns or ties, not beams.
2. Transverse loads and couples: A beam is specifically a member oriented so that the applied loads and moments act perpendicular (transverse) to its longitudinal axis, causing it to bend and develop internal shear force and bending moment; this is exactly the defining characteristic of a beam.
3. Twisting moment: A member primarily subjected to a twisting (torsional) moment about its own axis is a shaft, not a beam.
4. No load, with a specific orientation and cross-section: A structural member is defined by how it carries load, not by being unloaded with a particular geometry.

The defining feature of a beam is that it resists transverse loads and bending couples through internal bending and shear.

Therefore, the correct answer is transverse loads and couples.