There is really no uniform standard for determining the structure of heavy steel and light steel structure. Many experienced designers or project managers often cannot fully explain it, but we can consider and judge with some data:

1. Lifting weight of the plant: 25 tons or more, which can be considered as heavy steel structure.

2, the amount of steel per square meter: greater than or equal to 50KG / M2, can be considered a heavy steel structure.

3, the main component steel plate thickness: greater than or equal to 10MM, light steel structure used less.

In addition, there are some reference values: such as cost per square meter, maximum component weight, maximum span, structural form, height, etc. These can provide empirical data when judging whether the plant is heavy steel or light steel. Of course, many buildings are now Light and heavy steel are available. But there are some that we can say with certainty that it is heavy steel: eg petrochemical plant facilities, power plant buildings, large-span stadiums, exhibition centers, high-rise or super high-rise steel structures.

In fact, there is no heavy steel in the national norms and technical documents. In order to distinguish the steel structure of light-duty houses, it may be more appropriate to call the general steel structure “Pugang”. Because of the wide range of ordinary steel structures, it can contain a variety of steel structures, regardless of the size of the load, and even the many contents of the lightweight steel structure. The technical regulations for steel structures for light-duty houses are only specified for their "light" characteristics. Content, and the scope is limited to single-story portal frames.

Light steel is also a relatively vague term, and generally there are two kinds of understanding. One is the eleventh chapter of the current "Code for Design of Steel Structures" (GBJ 17-88) "Light steel structure of round steel and small angle steel", which refers to round steel and less than L45*4 and L56*36*4. The light steel structure made of angle steel is mainly used for small structures that are not suitable for reinforced concrete structures when the steel is lacking. It has been basically not used, so this steel structure design specification has basically been removed. The other is a single-layer solid belly-type rigid frame structure with a light roof and a light exterior wall (which can also be conditionally used for external walls) as stipulated in the Technical Specification for Steel Structures for Lightweight Houses of Portal Frames. The light weight here mainly means that the enclosure is made of lightweight materials. Since the former one has been canceled quickly, the current light steel meaning mainly refers to the latter.

It can be seen that the distinction between light steel and heavy steel is not the weight of the structure itself, but the weight of the enclosing material is still the same, and the structural design concept is consistent.