1、 Steel structure and concrete building have substitution relationship, which is the development trend of future building structure

According to the division of structural system, prefabricated buildings can be roughly divided into precast concrete structure (PC), steel structure (PS) and wood structure. At present, PC is still the main structure. According to the data of the Ministry of housing and urban rural development, among the newly started prefabricated buildings in 2019, PC structure accounts for 65%, steel structure accounts for 30%, and wood structure accounts for about 1%.As a rising prefabricated building, steel structure is different from precast concrete structure in that its main load-bearing components are all made of steel, which are composed of steel beams, steel columns, steel trusses and other components made of profiled steel and steel plates. The welding seams, bolts or rivets are usually used to connect the components on site.At present, more than 80% parts of steel structure building can be processed in the factory, and can be easily removed. Some products and materials can be recycled, and can cover most of the downstream corresponding to the field operation mode. It is an important representative of green building.

Steel structure has superior performance, which is the substitute of traditional concrete structure.Compared with the traditional concrete structure building form, steel structure building has three major characteristics of “high, large and light”. It is easy to realize the standardization of design, industrialization of components and parts production, construction mechanization and assembly. Steel structure building is the substitute of traditional concrete structure building.In addition, the steel structure has good performance characteristics: first, the steel structure has light weight, only about 30% ~ 50% of the traditional reinforced concrete building, and its strength is very large; second, the steel structure occupies a small area, and the space utilization rate is high, and the housing rate is increased by 5% ~ 8% compared with the traditional reinforced concrete residence; third, the steel structure has good ductility and excellent seismic performance; fourth, the steel structure construction efficiency is high, which can be improved by 4The construction period is only one-third of that of traditional buildings, and the construction period of 30-50 storey steel structure project can be shortened by about 8-12 months; fifthly, the energy-saving and environmental protection of steel structure can effectively reduce the amount of construction waste, achieve energy conservation of more than one third, 100% of steel can be recycled, and carbon emission can be reduced by more than 35%, which is in line with the concept of sustainable development.

The novel coronavirus pneumonia outbreak and other emergencies further highlight the advantages of steel structure construction.The novel coronavirus in Wuhan is a temporary hospital built by the fire god mountain and Raytheon hill hospital. The light steel structure is the main body, and the steel structure box type housing is used as the assembly mode. As the two hospitals adopt standardized and modular design, the most mature and finished industrial products are assembled, which greatly reduces the workload of the field work and achieves the maximum efficiency, such as fire.Shenshan hospital can be installed on the fourth day of construction, and the time from commencement to delivery is only about 10 days.In addition to Wuhan, many regions of the country have also launched the reconstruction and expansion projects of epidemic prevention hospitals, which further highlights the performance advantages of high construction efficiency and short construction period of steel structure buildings.

The downstream demand of steel structure is still mainly concentrated in commercial real estate and venues, and non residential steel structure buildings are expected to achieve a growth rate no less than GDP in the future.According to the analysis of the proportion of different building types in certain scale steel structure projects in China in 2017, commercial real estate accounts for 33%, stadiums accounts for 24%, and workshops account for 18% of the downstream demand of steel structures, while residential buildings account for only 4% of the whole steel structure projects, schools and hospitals and other fields only 1%, and schools, hospitals and residential areas still account for a low proportion. We conservatively predict the proportion in 2019This is similar to 2017.At present, the downstream demand of steel structure is scattered, and most of the plates are closely related to industry, real estate, construction industry and transportation industry. We predict that the annual growth rate of steel structure output of non residential buildings in China will not be lower than the growth rate of real GDP in the future.

According to the calculation, the penetration rate of steel structure buildings in commercial real estate and stadiums is close to 58%, and that of factory buildings is close to 40%. However, the penetration rate of steel structures in scientific research, schools, hospitals and residential areas is still low.We believe that at present, the application of steel structure in commercial real estate and stadiums has been relatively mature, and the fields of residence, school and hospital may become the “main battlefield” for the next development of steel structure buildings.

2、 The penetration rate of steel structure in residential area is low, which is expected to contribute to the industry output in the future

At present, the prefabricated buildings vigorously promoted by the Ministry of housing and urban rural development mainly refer to prefabricated houses, that is to increase the proportion of prefabricated houses in newly built houses.According to the National Bureau of statistics, the proportion of new housing construction area in the end of 2019 is more than 70%. Therefore, we believe that the ratio of “newly built prefabricated building area / newly started building area of that year” in the prefabricated building planning formulated by various provinces and cities can reflect the penetration of prefabricated housing in various regions to a certain extent, and the policy level is vigorously promotedIn fact, the prefabricated building is to increase the proportion of prefabricated residential buildings in new residential buildings.

The degree of public acceptance is relatively low, and the penetration rate of steel structure residence is only about 1%, which is expected to contribute incremental demand for the industry in the future.At present, the consumer’s acceptance of steel structure residence is low, mainly due to two aspects

One is the lack of understanding of the performance advantages of steel structure residence.At present, the architectural designers of Chinese traditional architectural design institutes lack in-depth understanding of the characteristics of flexible layout, large space and rich house type of steel structure residence. It is easy to use steel members instead of reinforced concrete components simply based on the design concept of traditional concrete structure residence, which makes the advantages of steel structure residence not fully play.However, structural designers have a direct misunderstanding on the fire resistance and corrosion resistance of steel structure residence, which makes it difficult to accept the application of steel structure in residential buildings. They often deny the steel structure residential scheme at the stage of determining the residential scheme, and prefer to choose the traditional concrete structure residential scheme.

Second, the comprehensive benefits of steel structure housing are not well understood.Project cost is the most intuitive economic index, and also the most important aspect in project operation.When consumers buy a house, the main concern is also the price of the house.Developers and consumers are more willing to accept the traditional concrete structure residence and brick concrete structure residence with lower direct cost, and lack of analysis and understanding of the comprehensive cost of steel structure residence in the whole life cycle, including design cost, procurement cost, labor cost, waste disposal cost, capital turnover cost, housing acquisition rate, environmental and ecological benefits, etc., which limits the steel structure housingMarket promotion.

Under the background of improving the assembly rate, the advantages of steel structure are expected to gradually appear in the future, and the space for improving the penetration rate of residential sector is larger (the target penetration rate of some provinces will reach 10% in 2022).According to our calculation, the increment of residential steel structure consumption in 2025 is expected to reach 17.41 million tons compared with that in 2019, contributing about 3.3% per year to the growth of industrial output. Steel structure residential buildings may become an important market for prefabricated buildings in the next stage.

3、 The policy inclines, superimposes the cost to close, the steel structure housing enters the rapid rise period of the industry development

In 2019, the relevant policies of steel structure housing will be strengthened, and the policy inclination is a major change at the industry level.After reviewing the relevant policies of prefabricated buildings in China, we believe that before 2019, the residential sector has no obvious emphasis on precast concrete (PC) and steel structure (PS).In March 2019, the Ministry of housing and urban rural development proposed to promote the steel structure residential pilot work for the first time, and then Shandong, Zhejiang, Hunan and other places successively issued pilot schemes. Zhejiang proposed that “by 2020, the proportion of steel structure prefabricated housing in the newly built prefabricated residential area should reach more than 12%, and Jiangxi proposed that” by 2022, the proportion of newly built prefabricated residential buildings in the whole province will account for newly built residential buildings “The proportion of residential buildings is more than 10%, and the pilot scheme is more quantitative.In June, the Ministry of housing and urban rural development issued the industry standard of prefabricated steel structure residential building, which was put into effect in October. It has made detailed specifications in the integrated design, component production, construction installation and quality acceptance, use and maintenance and management of steel structure residence, so as to promote the gradual formation of relevant industry standards.At the national housing and urban and rural construction work conference in December, it was emphasized once again that the pilot project of steel structure prefabricated housing construction should be vigorously promoted in 2020, the task target was further refined, and the steel structure pilot housing construction opened the application space of steel structure.

We believe that the penetration rate of prefabricated buildings is still expected to rise rapidly in the next five years.However, another trend worthy of attention is that all localities will further standardize and tighten the evaluation standards for prefabricated buildings. On May 25, Qingdao Bureau of housing and urban rural development issued the notice on further standardizing the evaluation of prefabricated buildings in Qingdao. We believe that in the future, the determination of the assembly rate and whether it meets the prefabricated building standards or not will become more strictThe sample is expected to enter the stage of high-quality development, and the permeability of steel structure, which can effectively improve the assembly rate, is expected to increase.

Another change in the industry is that the cost disadvantage of steel structure relative to concrete structure is obviously narrowed under the condition of continuous rise of concrete price and labor cost.According to the data in the consumption quota of prefabricated building projects issued by the Ministry of housing and urban rural development in 2017, the material cost and labor cost are the most important components of the construction and installation cost of prefabricated housing, and they account for more than 80% of the construction and installation cost.In precast concrete structure, the material cost increases with the increase of prefabrication rate, while the labor cost decreases with the increase of prefabrication rate.With the labor cost in the upstream channel and the difficulty of recruitment, the cost advantage of fabricated steel structure will gradually appear, and the cost gap between concrete structure and steel structure is expected to gradually narrow.Since 2017, with the rapid rise of cement and gravel prices, the concrete market is currently in short supply due to the shortage of sand and gravel aggregate, while the steel price has dropped from a high level after 2017 and 2018. The cost advantage of concrete structure relative to steel structure has gradually narrowed, and the price deterioration is expected to be significantly improved.

Considering the factor of government subsidy, we estimate that the steel structure residence is expected to be equal to the traditional cast-in-place cost in 2024-2025.Generally, the cost of residential buildings is divided into four categories: direct cost (labor cost, material cost, machinery cost), indirect cost (organization measure cost, management fee, regulation fee), profit and tax. Since the “consumption quota of prefabricated building engineering” was published in 2017, it is assumed that the costs of cast-in-place and steel structure residence in 2019 will remain at the level of 2017 (in fact, after 2017)Concrete prices have risen significantly, while steel prices have fallen from a high level).

Under the neutral calculation, we believe that the steel structure residence is expected to be equal to the traditional cast-in-place cost in 2024-2025.With the continuous closure of steel structure and cast-in-place building cost, the steel structure construction period is short and the housing rate is high, which further highlights the advantages of steel structure building.As the material cost is the most important factor affecting the construction cost, we assume that the change range of material cost of steel structure residence is – 4% ~ 0%, and that of cast-in-place concrete material cost is 1% ~ 5%. Through sensitivity analysis, we judge that the construction cost of steel structure residence and concrete residence can be leveled as early as 2022, and it needs to be in 2031 at the latest.