There is no uniform standard for determining the structure of heavy steel and light steel structures, but some data can be taken into account and judged.
1, plant crane lifting weight: greater than or equal to 25 tons, can be considered as heavy steel structure.
2, the amount of steel used per square metre: greater than or equal to 50KG/㎡, can be considered a heavy steel structure.
3, the thickness of the main components steel plate: greater than or equal to 10MM, the light steel structure used less.
In addition, there are some reference values: such as cost per square metre, maximum component weight, maximum span, structural form, eaves height, etc. The above can provide empirical data when judging whether the plant is heavy or light steel, but of course many buildings are now light and heavy steel. But there are some that we can say with some certainty are heavy steel: such as: petrochemical plant facilities, power plant plants, large-span stadiums, exhibition centres, high-rise or super high-rise steel structures.
In fact, there is no such thing as heavy steel in the national codes and technical documents. To distinguish light housing steel structures, it is perhaps more appropriate to call general steel structures “normal steel”. Because the scope of ordinary steel structure is very wide, can include a variety of steel structures, regardless of load size, and even including many elements of light steel structure, light housing steel structure technical regulations only for its “light” characteristics and provides some more specific content, and the scope is only limited to single-storey portal frame.
Light steel is also a rather ambiguous term, which can be understood in two ways. One is the current Code for the Design of Steel Structures (GBJ 17-88), Chapter 11 “Light Steel Structures of Round Steel and Small Angles”, which refers to light steel structures made of round steel and angles smaller than L45*4 and L56*36*4.
It can be seen that the difference between light and heavy steel is not in the lightness of the structure itself, but in the lightness of the envelope material to which it is subjected, but in the concept of structural design is still the same.
Taking the steel structure plant as an example, the lifting adopts the principle of “first in the middle, then outside, first column, then beam, first down, then up”, forming a stable frame system in the middle of the plant, then advancing to both ends and symmetrically installing the rest of the steel columns and beams in the following order.
→ unloading of the steel components → inspection of the components on site → direct lifting of the car crane into position → temporary tightening of the footing bolts → temporary tensioning of the cable ties → adjustment of the axial position and verticality of the steel columns → tightening and welding of the steel column bolts and column footing plates → installation of the next steel column → installation of the ties between the steel columns → formation of the first stable lattice system → assembly of the steel roof frame on the ground into a whole and lifting of the double machine into position to form the first steel roof frame → Symmetrical installation of columns and roof frame system on both sides → …… → and so on → Steel structure installation completed and structure acceptance.