Under vertical loads, which property is most critical for preventing failure in concrete?

• A. Compressive strength
• B. Tensile strength
• C. Flexural strength
• D. Shear strength

Answer: (A)

When a member carries vertical loads, it primarily experiences compression. Concrete is strong in compression and fails mainly by crushing its core when the compressive stress reaches its limit. That makes the compressive strength the controlling property for how much load the element can safely carry before failure occurs. The other properties matter in different situations: tensile strength is less critical here because concrete is weak in tension and reinforcement typically handles tensile forces; flexural strength becomes important when bending induces tension in the concrete near the tension face, but reinforcement shifts the limiting condition to the compression zone; shear strength matters more in scenarios with significant shear or eccentric loading.