The characteristics of the steel structure are as follows: the steel structure has good heat resistance, but poor fire resistance: experiments have shown that the performance of the steel does not change much from room temperature to 150 ℃, and the strength and plasticity change greatly after 150 ℃. When it drops to zero, it completely loses its bearing capacity and improves the fire resistance rating of the steel structure by half. The structure is usually wrapped with concrete or bricks, or it can be coated with a fireproof coating. When the thickness of the fireproof coating is 15mm, the fire resistance limit of the steel structure reaches 1.5h.

       1. Single-storey: A building with only one floor is a single-storey building, which includes industrial plants (single-storey height above 6-8 meters), civil buildings (2.2 to 3 meters above), agricultural sheds (2.2 meters above) and other buildings.

       2. Multi-storey: refers to 4-6 storey buildings.

       3. High-rise: refers to buildings with more than 10 floors and a total height of less than 100 meters.

       4. Super high-rise: refers to buildings with a height of more than 40 floors and a height of more than 100 meters.

       5. High-rise, super high-rise, mainly adopts steel-concrete structure, such as: cross column, box column and other structural forms.