Structural members – what loading defines a strut? In a frame structure, a strut is a load-carrying member that is primarily subjected to which type of loading?

Introduction / Context:
Terminology distinguishes structural members by their primary internal force resultants: ties resist tension, struts resist compression, beams resist bending, and shafts resist torsion. Correct identification is essential for design checks such as buckling versus yielding.

Given Data / Assumptions:

• Member is straight and slender compared to its cross-section.
• Ends provide axial alignment; eccentricities are small.
• Loads are primarily along the member’s longitudinal axis.

Concept / Approach:
A strut is a compression member that carries load principally through axial compressive stress. In slender struts (columns), stability (buckling) often governs design, whereas in stocky struts, material crushing may control. The term applies across materials: steel, timber, reinforced concrete, aluminum, and composites.

Step-by-Step Solution:
Identify the defining internal force → axial compression.Exclude other primary actions: tension (tie), bending (beam), torsion (shaft).Thus, “axial compressive loads” is the correct characterization.

Verification / Alternative check:
Design codes classify compression members (struts/columns) and prescribe slenderness limits, effective length factors, and buckling curves specifically for axial compression.

Why Other Options Are Wrong:

• Tension defines a tie/rod, not a strut.
• Torsion and transverse loads describe shafts or beams, not struts in their primary role.
• Combined actions may occur in practice, but the defining action of a strut is axial compression.

Common Pitfalls:
Ignoring small eccentricities that can introduce bending; in design, check combined compression and bending as required, but the member is still termed a strut.

Final Answer:
Axial compressive loads