1. The steel has good toughness, plasticity, material uniformity, high structural reliability, suitable for bearing impact and dynamic load, and good seismic performance. The internal structure of steel is homogeneous and nearly isotropic. The actual performance of the steel structure accords with the calculation theory. So the reliability of steel structure is very high.

2. The material has high strength, light weight, high steel strength and high elastic modulus. Compared with concrete and wood, the ratio of density to yield strength is relatively low, so under the same stress conditions, the steel structure has small section, light weight, convenient transportation and installation, and is suitable for large span, high height and heavy load structures.

3. The steel structure has good sealing performance. Because the welding structure can be completely sealed, it can be made into high pressure vessels, large oil pools and pressure pipes with good air and water tightness.

4. When the temperature is lower than 150 ℃, the properties of the steel change little. Therefore, the steel structure is suitable for the hot workshop, but when the surface of the structure is radiated by the heat of about 150 ℃, the heat insulation plate should be used to protect it. When the temperature is 300 ℃ - 400 ℃, the strength and elastic modulus of the steel decrease significantly. When the temperature is 600 ℃, the strength of the steel tends to zero. In buildings with special fire protection requirements, steel structures must be protected with refractory materials to improve the fire resistance rating.

5. The corrosion resistance of steel structure is poor, especially in humid and corrosive environment, it is easy to rust. Generally, steel structure shall be derusted, galvanized or coated, and maintained regularly. For offshore platform structures in seawater, special measures such as "zinc anode protection" should be taken to prevent corrosion.

6. The manufacturing and installation of steel structure is highly mechanized, and the steel structure components are easy to be manufactured in the factory and assembled on the construction site. The factory mechanized manufacturing of steel structure components has the advantages of high precision, high production efficiency, fast assembly speed and short construction period. Steel structure is one of the more industrialized structures.