Steel is ubiquitous in construction, from beams supporting roofs to the framework of entire buildings, to the tools you use. However, steel is not just one thing - there are many different types of steel and different shapes of steel, each with their own uses and purposes.
Structural steel refers to steel that meets specific strength and formability grades. Formability is measured by the elongation rate after the tensile test. Structural steel is generally used for load-bearing purposes where the strength of the steel is an important design criteria. Structural steel can be subdivided into: carbon structural steel, high-quality carbon structural steel, low-alloy high-strength structural steel, alloy structural steel, spring steel, weather-resistant structural steel, easy-cutting structural steel, non-quenched and tempered mechanical structural steel, etc. Compared with ordinary carbon structural steel, high-quality carbon structural steel has lower content of sulfur, phosphorus and other non-metallic inclusions.
Structural steel frame construction is a metal used for building materials. It is fundamentally defined as steel optimized for construction purposes - as opposed to steel that may be used for engineering tools, or stainless steel commonly used for kitchen surfaces and appliances. Structural steel is typically carbon steel, meaning its chemical composition includes both iron and carbon. Structural steel is any type of steel with a carbon content that does not exceed 2.1% of its total weight. The higher the carbon content, the higher the yield strength of the steel - meaning it has less ductility, or is less likely to bend or warp under pressure.
Structural steel is inexpensive and durable: compared to other materials, steel is cost-effective, has a long lifespan, and is easy to mass-produce structural steel products. Steel also has a high strength-to-weight ratio, meaning it is lightweight compared to the weight it can support. A 40x40cm structural steel beam can do the same job as a 100x100cm reinforced concrete beam.
Structural steel's ductility: structural steel has good ductility. It has elasticity and can bend and yield slightly, making it less likely to fail suddenly. Its toughness or energy-absorbing ability means that structural steel can withstand impact and bear heavier loads without sagging.
Structural steel is versatile: last but equally important, structural steel is versatile. Structural steel can be relatively easily modified, shaped, and formed.