With the increasing pressure of energy conservation and emission reduction in China, the country pays more and more attention to environmental protection and natural resource protection. The development of green buildings has been written into the national “12th Five Year Plan”, which is undoubtedly a rare development opportunity for the steel structure industry. According to the 12th Five Year Plan for the development of the construction industry officially released by the Ministry of housing and urban rural development, the annual growth of the total output value and added value of the construction industry in China during the 12th Five Year Plan period should be more than 15%. The 12th Five Year Plan for the development of the construction industry also requires that the energy consumption per unit added value of the construction products during the 12th Five Year Plan period will decrease by 10%, the consumption of screw steel will reach 45% of the total consumption, and the proportion of steel structure engineering will increase. The engineering design of the new construction project should all conform to the national building energy saving standard, and the construction of the new construction project should conform to the national building energy saving standard; the contribution rate of the whole industry to the resource-saving society is significantly increased. In response, some analysts said that this means that China’s steel structure industry will usher in a rapid development opportunity. It is expected that the annual output of China’s steel structure will reach 50-65 million tons at the end of the 12th Five Year Plan.
Steel structure is closely related to green building
At the 11th National Symposium on modern structural engineering held recently, Fang Hongqiang, an expert member of the construction steel structure Committee of China Construction Metal Structure Association, said: “a new construction system is likely to break through the industrial boundary between the real estate industry, construction industry, metallurgy industry, machinery and equipment manufacturing industry and national strategic resources, and become a new industrial system. This is the steel structure building system that the industry is generally optimistic about. “
Steel structure building is the representative of green building. The promotion of steel structure is an important part of the development of circular economy in the construction industry and the transformation and upgrading of the traditional civil construction industry. Steel structure building not only has the excellent performance of “light, fast, good and economical”, but also has the advantage of recycling. Steel structure has the advantages of high strength, light weight, good anti-seismic performance, low foundation cost, large building area, high building quality, suitable for industrial and standardized production, dry and green construction, suitable for different climatic conditions, not affected by construction season, low comprehensive cost, etc. at the same time, steel structure can also reduce the pollution of construction waste on the environment, in the whole life cycle It can be recycled during the period. Fang Hongqiang said that the steel structure building conforms to the development direction of energy conservation and emission reduction and circular economy in China and is one of the structures with the smallest impact on the urban environment.
Steel structure has been widely used in developed countries, which is called the main representative of green building. In Europe, green building is called ecological building or sustainable building. China’s green building refers to a building that can save resources (energy, land, water and materials), protect the environment and reduce pollution to the maximum extent, provide people with healthy, applicable and efficient use space and live in harmony with nature in the whole life cycle of the building.
Obvious technical advantages of steel structure building
The average life span of buildings in Europe and America is more than 80 years. In contrast, the average life span of buildings in China is only 30 years, less than 60% of the minimum service life of national standards. In the process of repeated construction, China has created two world firsts: while consuming the most cement and steel in the world, it also produces the most construction waste in the world – up to 400 million tons per year, accounting for 30% – 40% of the total waste. Construction waste is piled up and buried around the city, which is in the situation of “garbage besieged city”. It not only occupies the land, but also contains all kinds of harmful chemicals, which seriously corrode the surface and pollute the underground water source, causing great harm, and posing a threat to the living environment of human beings. In addition, the construction waste has also cut off the historical context of the city, weakened the cultural heritage of the city, and destroyed the city style.
Because reinforced concrete structure and masonry structure need manual operation, in the field of wet construction, the noise and dust produced during the construction seriously endanger the health of workers. More importantly, the recycling rate of building materials of reinforced concrete structure and masonry structure is very low. The pollution of construction waste on the environment and the adverse impact on future generations after reaching the life cycle have attracted the widespread concern and general concern of experts at home and abroad. In addition, there is a shortage of high-quality mineral materials for burning cement, and the sand and stone for preparing concrete are very tense in many places. In some areas, sand mining has seriously damaged the riverbed and vegetation.
Steel structure building should firmly establish the design concept of green building: according to the concept of “zero resource, zero energy consumption, zero emission, zero pollution, Zero construction site, zero distance”, establish a new model of building life cycle development and construction from planning, design, construction, use to demolition, develop, design and build a new generation of modern steel structure that meets industrialization, standardization and industrialization Construction of residential building products.
Compared with the traditional civil construction, the steel structure building has four excellent performances of “light, fast, good and economical”. The ratio of volume weight and strength of steel is smaller than that of concrete and wood. Under the same conditions, the overall weight of buildings with steel structure is the lightest. Steel structure is easy to be manufactured mechanically, with high accuracy, convenient installation and short construction period. It is the structure with the highest degree of industrialization in engineering structure. Steel structure buildings have small environmental damage, good seismic performance and are suitable for different climate conditions Steel structure can also save the cost of foundation, save water and control the cost. At the same time, it can also be reused to reduce construction waste.
He compared the steel structure building with the wood structure building with a common multi-storey frame structure building of 3-4 floors. “If the wood structure is adopted, 40 to 50 trees of wood age of about 10 years are generally needed; and if the steel structure is adopted, only 6 scrap cars of steel are needed.” Fang Hongqiang said. In recent years, there have been several destructive earthquakes in the world, which make the most important advantage of steel structure buildings – good seismic performance – stand out. According to the actual situation in China, the promotion of steel structure residence in the post disaster reconstruction is not as powerful as the pulling force of concrete building to restore the local economy, because the steel structure residence is factory production, assembly in the construction site, can save a lot of labor.
Development of steel structure building is the general trend
In 2009, the consumption of steel for construction in China accounted for 50% – 60% of the total steel output, which is equivalent to the average consumption level of steel in the world. However, the consumption of steel in China’s construction is mainly used for steel bars, steel wires, steel strands, etc. in the real sense, the steel for steel structure construction only accounts for about 10%. In China, the building area of steel structure buildings accounts for about 2%, while that of developed countries accounts for 40% ~ 60%. In Japan, steel structure buildings account for about 50% of the total construction; in South Korea, steel structure buildings account for about 20% of the total construction. It can be seen that China’s steel consumption for steel structure construction is seriously low, which is a huge contrast with the rapid growth of China’s steel output, which is also a main reason for the overall supply of steel in China to exceed the demand.
He pointed out that according to the latest data, in 2010, China’s steel production was more than that of Japan, the United States and other countries ranked in the second to the tenth place, accounting for 43.3% of the world’s steel production. The continuous growth of steel production in China has laid a solid foundation for the development of steel structure buildings in China.