Beams are structural elements that withstand loads primarily by resisting deflection (bending). Which word best describes this action?

• A. Beams
• B. Columns
• C. Slabs
• D. Cables

Answer: (A)

Beams resist loads primarily through bending, which is the flexural action that produces deflection along their length when a transverse load is applied. A beam is designed with enough flexural stiffness (EI, where E is the modulus of elasticity and I is the moment of inertia) to keep that deflection within allowable limits. This bending resistance is what distinguishes beams from other members: columns mainly carry axial compression; slabs distribute loads and can bend, but their primary role isn’t resisting bending in the same way a dedicated beam does; cables carry tension and don’t resist bending at all. So the term that best describes the action of resisting deflection through bending is embodied by the beam itself—the member whose primary behavior under such loads is flexure.