1.Steel has high strength, light weight and high elastic modulus.Compared with concrete and wood, the ratio of density to yield strength is relatively low.Therefore, under the same stress state, the steel structure component has small section and light weight, which is convenient for transportation and installation, and is suitable for large span, high height and heavy load structure.

      2.The steel has good ductility, good plasticity, uniform material and high reliability.It is suitable for bearing impact and dynamic load with good seismic performance.The internal structure of the steel is homogeneous, close to the isotropic homogeneous body.The actual working performance of steel structure accords with the calculation theory, so the steel structure has high reliability.

      3.steel structure manufacturing and installation of high degree of mechanization, steel structure components in the factory and construction site is easy to assemble.The mechanical manufacturing of steel structure parts has the advantages of high precision, high production efficiency, fast on-site assembly and short construction period.Steel structure is the most industrialized structure.

      4.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 tanks, pressure pipes, etc., with good sealing and water tightness.

      5.The steel structure is heat-resistant and not fire-resistant.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 the heat radiation on the surface of the structure is about 150 ℃, so the heat insulation board 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 about 600 ℃, the strength of 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.

      6.The corrosion resistance of steel structure is poor, especially in humid and corrosive medium environment.In general, steel structures shall be derusted, galvanized or coated and shall be maintained regularly.Special measures such as “zinc block protection” should be taken to prevent the corrosion of offshore platform structure in seawater.

      7.Low carbon, energy saving, green and environmental protection, can be reused. The demolition of steel structure engineering will not produce construction waste, and the steel can be recycled.