Fabricated steel structure building is not a new thing in China, especially in recent years, the national policy level of warm air blowing frequently, the related policies have been implemented. However, there is no denying that the status seems to be very different: on the one hand, prefabricated steel buildings in public buildings widely used, high acceptance; On the other hand, the prefabricated steel structure building in the huge market in the residential sector of the application of little, difficult. From the technical and economic perspective, what is the problem, the following brief to make a superficial comb and analysis.
1. Are technical standards lacking?
There is a lack of standards for prefabricated steel structures. It seems that there are quite a lot of people who hold this view, and even lead to the preparation of relevant standards in an urgent way.
In fact, the domestic steel structure related technical standards (including design and construction, acceptance and so on) is not lack, and in the promotion of steel structure public buildings. For residential steel structure, there are two typical cases: First, the structure specification does not support the idea and request of the design of certain residential buildings; Second, the proprietary structural system developed by some companies is in conflict with the existing norms and needs special demonstration. These conditions exist, but they are not decisive factors in the constraints. At the same time, these problems will be gradually resolved in the preparation and revision of standards in the near future.
There are also related product standards, testing standards and application technical standards for building envelope, internal and electromechanical components of prefabricated steel structures. Newly introduced and developed parts are also gradually compiling relevant standards. However, the quality acceptance of component parts of fabricated steel structure, a large part of the factory production will involve the supervision of products, how to implement, in the current standard level there are still some problems.
The existing Evaluation Standard for Industrialized Buildings is mainly concrete structure, but does not reflect the advantages and characteristics of steel structure. There are disputes on the calculation of assembly rate of fabricated steel structure buildings. At present, this standard is under revision.
Therefore, in general, the statement of lack of standards for prefabricated steel structure is not accurate, the current standard system is also in accordance with the needs of prefabricated steel structures gradually perfect.
2. Is the technical system mature?
In the process of popularizing the fabricated steel structure building, there are several technical problems which are often questioned.
(1) Fire and corrosion resistance performance
It is generally considered that steel structure fire and corrosion protection performance is not good, using paint for protection, paint life is generally only about 10 years, and the design life of the building is far from. Because of the different conditions of use, public buildings allow for later inspection and maintenance, so less challenge. And residential steel structure is basically impossible to use during the indoor inspection and maintenance, suddenly seems to become fatal problem. This misunderstanding is widespread even among technical personnel in the industry.
In fact, residential steel structure in the indoor normal environment corrosion is extremely limited, even if the initial painting for a long time failure, corrosion is also in a controllable range, will not affect the structural safety. The use of steel structures built decades ago in the United States and Japan has been fully illustrated by these problems. Even, according to the experience of Japan, the current construction of steel structures has been widely no longer anti-corrosion coating. In addition, the fire protection problem of steel structure can also be handled through the paste coating of fire protection sheet, more reliable than fire protection paint.
Therefore, the problem of fire prevention and corrosion protection of prefabricated steel structures is not a big problem in technology, more is a problem of understanding.
(2) Living Comfort
Steel structure of the public building comfort problem is not prominent, criticized, mostly residential. This is often the residential building envelope components and structural technology problems caused.
In the past years, due to the problems of supporting resources and application technology, Result in improper selection of enclosure part, or technical immaturity, engineers use inappropriate wall structure, resulting in external wall cracks, seepage, sound insulation, insulation and so on.
In fact, with proper selection of components and reasonable construction of the enclosure system, prefabricated steel buildings can achieve the same living comfort as concrete shear walls. These problems are being improved with the gradual maturity of building envelope components and the progress of engineers in technology.
(3) Building accessories
In the past years, the assembled steel housing industry chain is not sound, supporting industries far behind the development of steel industry itself, supporting the exterior wall panels, floors, walls and other options are not large, the price is high. The steel structure of public buildings using curtain wall and floor bearing plate in the majority, matching problem is not large.
In recent years, mature products directly from abroad, domestic introduction and independent research and development of the relevant new building materials enterprises are booming, assembly building industrial parks and demonstration bases bloom everywhere, optional parts have been basically formed a system.
(4) Building System Integration
The experiences of the past years show that the steel structure engineer-led model is unfavorable to the popularization of fabricated steel structure building. This problem is not prominent in the individual design of steel structure public buildings, but in the prefabricated steel structure residential, it is very important.
The construction of prefabricated steel structure residence is a process of building system integration to realize the whole building function and satisfy the user’s needs. More and more enterprises will focus on the construction of professional leadership, building system integration, building products. In other words, it is a product development led by the product manager. Any problem that affects the product function may result in the product being unable to satisfy the customer.
Therefore, it is necessary to abandon the traditional practice of replacing concrete structures with steel structures and treat them from the perspective of system engineering. With building function as the core, structural layout as the foundation, with industrialized envelop and internal components as the support, the overall improvement of steel structure residential use function and living quality. Comprehensive consideration needs to be given to building functions, structures, enclosures, internals, electromechanical, Realize the coordination and integration of Huxing, facade, structural system, enclosure system, pipeline system, fire prevention and internal installation, and finally realize “building a house like a car.”
3. Is the cost too high?
High cost is the key factor which hinders the development of prefabricated steel structure buildings, especially residential buildings. Especially compared with the traditional reinforced concrete buildings, the cost of steel structure is obviously higher. That seems to be an impression ingrained.
In fact, in recent years, the price of steel products has been greatly reduced, supporting parts and components industry has gradually matured and formed a competitive situation, The cost of prefabricated steel structure residential has been basically close to the traditional concrete shear wall, and the construction period is shorter, the quality is better, the assembly rate is higher, more easy to get the local has gradually landed policy support.
From the review and analysis above, we can judge that the policy orientation, cost and technology of the fabricated steel structure building have shown a favorable trend at present, and it has come to a turning point of vigorous development. In addition to public buildings, in recent years, to days, Baosteel, Hangzhou Xiao, represented by a number of units, but also in the assembly of steel residential aspects of the corresponding technology research and development and industrial layout, industrial development of the spring has undoubtedly arrived.