Which material properties guide cross-section sizing for steel or concrete members?

Which material properties guide cross-section sizing for steel or concrete members?

• A. Color and texture of the material.
• B. Cost and manufacturability considerations.
• C. Yield strength, compressive strength, and tensile capacity.
• D. Durability alone.

Answer: (C)

Cross-section sizing is driven by the strengths of the materials involved. The amount of steel or concrete you can safely use in a member is dictated by how much stress the material can withstand without failing. For steel, the yield strength tells you when the metal starts to plastically deform, and the section must be sized so the stresses under load stay within that limit (often with the help of the allowable stress or strength design approach). For concrete, the compressive strength sets how much compressive stress the concrete can carry in the compression zone, while the tensile capacity in reinforced concrete comes from the reinforcement, whose own tensile strength or yield is critical. Together, these material properties determine the required cross-section to meet strength and stiffness requirements. Other factors like color, texture, or just durability or cost alone don’t set the structural size; they’re important for other reasons but not the primary criteria for strength-based sizing.

Cross-section sizing is driven by the strengths of the materials involved. The amount of steel or concrete you can safely use in a member is dictated by how much stress the material can withstand without failing. For steel, the yield strength tells you when the metal starts to plastically deform, and the section must be sized so the stresses under load stay within that limit (often with the help of the allowable stress or strength design approach). For concrete, the compressive strength sets how much compressive stress the concrete can carry in the compression zone, while the tensile capacity in reinforced concrete comes from the reinforcement, whose own tensile strength or yield is critical. Together, these material properties determine the required cross-section to meet strength and stiffness requirements.

Other factors like color, texture, or just durability or cost alone don’t set the structural size; they’re important for other reasons but not the primary criteria for strength-based sizing.