Answer & Solution
Answer: Option D
Solution:
Plastic Moment Capacity: This is the maximum bending moment a structural section can withstand before it starts to deform permanently.
Shear Force: Shear force acts parallel to the cross-section of a structural member.
Effect of Shear Force: When shear force is present, it reduces the area available to resist bending. Think of it like some part of the section is already 'busy' resisting shear, so it can't contribute as much to resisting bending. Therefore, the
plastic moment capacity decreases.
Axial Force: Axial force acts along the longitudinal axis of a structural member (either tension or compression).
Effect of Axial Force: Axial force also reduces the area available to resist bending. If there's compressive axial force, some of the material is already stressed in compression, leaving less capacity for resisting compressive stresses from bending. If there's tensile axial force, it can similarly reduce the effective area for resisting bending. Therefore, the
plastic moment capacity decreases.
In summary, both shear force and axial force reduce the plastic moment capacity of a structure.
