Which describes modulus of rupture?

• A. Compressive strength
• B. Elastic modulus
• C. Thermal conductivity
• D. Bending or tensile strength

Answer: (D)

Modulus of rupture measures how much bending stress a material can withstand before it fails. It represents the flexural (bending) strength of the material, usually found from a bending test such as a three-point or four-point flexure test. In bending, the outer fibers are put under tension as the beam curves, and the MOR corresponds to the stress at which the specimen breaks. It’s not a measure of stiffness (that’s the elastic modulus), nor of how well it conducts heat (thermal conductivity), nor of compression strength. For tilt-up panels, this value helps predict how the panel will resist bending under loads like wind, gravity, or connections, since failure most often occurs in bending.