Although steel structure project has a variety of advantages,there are some disadvantages as follows:
1 weak stiffness
In steel structure engineering, the characteristics of high strength,light material make the component not only has small cross section size ,but also composed of open or closed cross section by steel or steel plate.Compared with traditional concrete structure parts,this section has a bigger slenderness ratio,the resistance of lateral bending and torsion stiffness is maller than concrete component,thus,it's easy to lose the overall stability.Due to the high width-to-thickness ratio,it also easy to lose partial stability.So,in the steel structure design, these are relatively easy to create problems.
2 Good heat resistance, but poor fire retardancy
With the increase of temperature, steel performance is also changing rapidly.When heated more than 200℃,the steel texture start to change,tensile, compressive strength will reduce,when reaches 600℃, the steel turns into plastic state and lose the capacity of bearing.
3 Poor corrosion resistance
Steel product is easy to rust in damp environment, especially in a corrosive medium environment.So coating mass must be strictly controlled, and still need regular maintenance during use.
With the improvement of science and technology, for those steel members with strong corrosive medium and thin-wall,we can use galvanized and aluminized technology to effectively prevent the corrosion.
4 Under the condition of low temperature components are prone to brittle fracture
A large number of tests show that in minus temperature environment,the steel's plasticity and toughness will be gradually reduced, when reaches a certain temperature,it will sharply fell , this called the low temperature cold short, the temperature is called the critical brittleness temperature.