What characteristic makes structural steel suitable for load-carrying members in structures?

Structural steel is primarily chosen for load-carrying members in structures due to its economy and desirable mechanical properties. The mechanical properties of structural steel, such as high tensile strength, yield strength, and ductility, make it capable of supporting significant loads while maintaining structural integrity. Additionally, steel is relatively economical compared to other materials, allowing for cost-effective construction without sacrificing performance.

The combination of these properties allows engineers to design structures that are efficient, safe, and economically viable. When considering other properties, while thermal conductivity is a characteristic of steel, it does not contribute to its effectiveness in carrying loads. Similarly, a low weight-to-strength ratio is not typical of steel; it tends to have a high strength-to-weight ratio, which is advantageous. Lastly, corrosion resistance is a relevant concern for steel in various environments, but it does not define its capacity as a load-carrying material. Therefore, the best choice is the economy and desirable mechanical properties that make structural steel an ideal material for construction.