1、 Firstly, the advantages and disadvantages of lower steel structure and reinforced concrete structure are introduced

 Reinforced concrete structure refers to the structure made of reinforced concrete.The main load-bearing components are made of reinforced concrete.It includes thin shell structure, large formwork cast-in-place structure and reinforced concrete structure constructed by slip form and rising slab.A structure made of steel and concrete. 

Steel structure and reinforced concrete structure

Advantages of reinforced concrete structure:

 　　1.Good moldability: the newly mixed concrete is plastic and can be designed into structures or components of various shapes and sizes according to the needs.

 　　2.Good integrity: the integrity of cast-in-place reinforced concrete structure is good, and it has good seismic, anti explosion and anti vibration performance when the design is reasonable.

 　　3.Good durability: reinforced concrete structure has good durability.Regular maintenance and repair are not required under normal use conditions.

 　　4.Good fire resistance: compared with steel structure, reinforced concrete structure has better fire resistance.

 　　5.Easy to use local materials: sand and stone materials with large proportion used in reinforced concrete structure are easy to obtain local materials, and can effectively use industrial wastes such as slag and fly ash, which is conducive to environmental protection.

 Disadvantages of reinforced concrete structure:

 　　1.Self weight: the weight of reinforced concrete is about 25kn / m3, which is larger than that of masonry and timber.Although the weight of steel is smaller than that of steel, the section size of the structure is larger, so its self weight is far more than that of steel structure with the same span or height.

 　　2.Poor crack resistance: the tensile strength of concrete is very low, therefore, ordinary reinforced concrete structures often work with cracks.Although the existence of cracks does not necessarily mean that the structure is damaged, it affects the durability and beauty of the structure.When the number of cracks is large and the development is wide, it will also give people a sense of insecurity.

 　　3.Brittleness: the brittleness of concrete increases with the increase of concrete strength grade.

 The steel structure is mainly composed of steel beams, steel columns, steel trusses and other components made of H-beam, I-beam and steel plate. The welding seams, bolts or rivets are usually used to connect the components or parts.Because of its light weight and fast construction, it is widely used in large industrial plants, gymnasiums, gas stations, super high-rise and other fields.

 Advantages of steel structure:

 Light weight: the steel has high strength and flexibility. The self weight of the building is only one fifth of that of the brick concrete structure. It can resist the typhoon of 70 meters per second, so that life and wealth can be effectively maintained.

 Durability: the steel structure housing structure is composed of cold-formed thin-walled steel member system, and the steel bar is made of super anti-corrosion high-strength hot-rolled galvanized sheet, which can effectively prevent the corrosion of steel plate in the process of construction and application, and increase the service life of light steel components.The service life of the main structure can reach more than 50 years.

 Flexibility: steel structure can be designed at will, suitable for large-span structure, and can not use columns, saving effective space.With flexibility and richness.Large bay design, indoor space can be divided into multiple schemes, which can meet the different needs of users and bring huge design space to designers.

 Economy: the formation of steel structure building is very simple, and the self weight is very light.The formation of steel structure building is very simple, and its self weight is very light, so its total cost is one third of the general reinforced concrete structure.All dry construction, not affected by environmental seasons, not affected by water and electricity.

 Comfort: sandwich panel is the main thermal insulation and sound insulation material used in steel structure, and color steel sandwich panel and rock wool sandwich panel are the main wall products, which have excellent insulation and sound insulation effect.The insulation board with partition wall achieves better insulation effect.The light steel wall adopts high-efficiency energy-saving system, which does not need to worry about formaldehyde exceeding the standard. At the same time, it has good ventilation performance. It can make the air above the house form a fixed atmosphere to ensure the ventilation and heat dissipation needs of the roof outside.

 Energy saving and environmental protection: materials can be recycled 100%, truly green without purification.All adopt high-efficiency energy-saving frame, layer, wall, heat insulation, sound insulation, heat insulation effect is good, can reach 50% of the energy-saving norms.

 Disadvantages of steel structure:

 No fire resistance: when the temperature exceeds 250 ℃, the material changes greatly, not only the strength gradually decreases, but also blue brittleness and creep.When the temperature reaches 600 ℃, the steel enters the plastic state and can not continue to bear load.

 Brittle fracture: brittle fracture of steel structure may occur under low temperature and some conditions, and lamellar tearing of thick plate should be paid special attention to by designers and users. These problems can be solved.

 Poor corrosivity: it is in poor corrosivity. The steel structure should be thoroughly derusted before painting. The paint quality and coating thickness should meet the requirements of relevant specifications.In the design, damp and rain leakage should be avoided in the structure, and the dead corner of inspection and maintenance should be avoided as far as possible.The newly built steel structure usually needs to be repainted every certain time, so the maintenance cost is high. 

Advantages and disadvantages of steel structure and reinforced concrete structure

The reasons why steel structure engineering is not as popular as reinforced concrete structure in China is analyzed as follows

 First, cost.The amount of steel used in steel structure is much higher than that in reinforced concrete structure. The unit price of relevant materials should be Baidu.In addition, the domestic labor cost is much lower than that of European and American countries, so the advantages of steel structure off-site production site hoisting, fast construction period and labor saving have not been reflected in domestic projects.I have no ready-made steel structure and reinforced concrete structure cost comparison between China and the United States, but the difference is still very obvious.

 Second, market transformation takes time.As we all know, the domestic market is so large, and there are so many enterprises engaged in the design, construction, supervision and decoration of reinforced concrete structures. There is no great transformation demand for them to jump out of the familiar working area to engage in relatively unfamiliar steel structure design and construction.When a thing is done well and done many times, it naturally wants to use it all the time. This is the case for Party A, the Design Institute (design template), and construction (relevant experience, personnel, large machinery and equipment).Everyone knows that steel structure is the future direction, but transformation means time cost, personnel training cost, the crisis of production efficiency decline in the initial stage of transformation, and so on.

 Third, regional differences.Many parts of China are earthquake prone areas, the proportion of which is much higher than that of Europe and the United States (except California, it seems that there is no such area in the United States except California). The steel structure has a long self vibration period, poor structural rigidity, and its seismic performance is relatively inferior to that of steel concrete structure.From this point, it is reasonable not to choose steel structure in China.

 Fourth, environment and environmental protection needs.Most of the foreign projects adopt steel structure. Part of the reason is that the construction period is short, the noise is small, the pollution is small, the later disassembly or material recycling is convenient, and there is no waste.Think about the steel concrete structure construction site, the noise of concrete vibration, the noise of steel bar collision when laying the steel mesh, the dust of powdery raw materials blown by a gust of wind (of course, there are many improvements after the compulsory use of industrial concrete). If it is demolished later, in addition to a small part of materials can be recycled, the remaining concrete waste blocks will bring huge pollution and waste.It’s not that China doesn’t attach importance to environmental protection, but that foreign countries are indeed ahead of us in doing a good job, and we should catch up with them.

 Fifth, the psychological differences of consumers.Many consumers evaluate the quality of the house, still staying in the standards of “the thickness of the wall, the weak knot when knocking, stamping the foot hard, whether the floor will shake, whether the partition is not sound insulation, whether a closet can be hung on the wall”, and so on. The concrete structure housing just meets these standards, but the steel structure has low self weight and high ductility. The use of light partition wall leads to poor sound insulation, heat insulation and moisture-proof effect, so it will not be affected temporarily Chinese consumers accept it.To sum up, it is not surprising that the steel structure has a low popularization rate after spending a lot of money and efforts, and the products are still hard to please.