Since the reform and opening up, China's economy has developed rapidly, and large-scale urbanization is under way, and this process will continue for twenty or thirty years. During this period, all fields and industries are in a highly developed stage, and a large number of temporary buildings are needed to support the construction and future use of a large number of permanent buildings, structures and road and bridge traffic facilities. In addition, in industries that need long-term field work and open-air work, temporary houses that meet different requirements are needed during emergency needs, disaster relief, tourist peaks and festivals. As a result, various temporary buildings came into being. With the progress of the times, the improvement of working conditions and the need to build a harmonious society, the state has high requirements for the safety, applicability and improvement of living conditions of temporary buildings. At present, there are differences in various industries and regions of temporary buildings in China. Take the construction industry and urban traffic construction as examples. The construction site is used for temporary houses such as workers' dormitories, offices, canteens and warehouses. In the past, the simple shed built by small-angle tents was mostly used in the northern region, and then it was improved into a cement board house composed of 2-3 layers of small-angle steel bars and cement boards. In the south, bamboo sheds are often used; And multi-purpose container trailers that need long-term outdoor open-air operations. Nowadays, the use of light-weight steel composite houses is increasing, and the number of light-weight steel composite houses in temporary buildings in Beijing construction site is also increasing year by year, accounting for more than half of the total. The temporary houses in Shenzhen construction site and urban rail transit construction site in Guangdong Province are almost all light steel structure composite houses. As a temporary building, light steel structure composite houses have many advantages compared with other types of temporary buildings, so the proportion of light steel structure composite houses in temporary applications is increasing.
1). Characteristics of light steel structure composite residence
Light steel structure composite building generally refers to a 1~3-storey temporary building composed of light H-beam, cold-formed thin-walled beam, round beam, small angle beam, profiled steel plate and sandwich panel. This light steel structure composite residence is the simplest and most industrialized light steel structure residence.
According to the different types of structures, light steel structure composite houses can be divided into plate structure, frame supporting structure, frame structure and box unit structure. Light steel structure composite houses have the following characteristics:
(1). Light weight: the combined house weighs about 15~30kg/m2.
(2) Simple and quick assembly: all components and plates of the house are prefabricated in the factory and transported to the site for assembly with bolts, self-tapping screws, rivets and other connectors. The building was built quickly. According to different housing models, generally 1 worker 1 day can be installed for 20~50m2. A two-story 200-square-meter combined room can be installed by six workers in a day and a half, and it can be done immediately.
(3) The design standard is finalized and the combination is flexible and diverse; The parts produced by the factory have high machining accuracy and good quality.
(4) The house can be disassembled and moved, and the transportation and assembly are simple. A car can transport a combined house of about 500 square meters.
(5) The light steel structure composite house has the advantages of light weight, simple foundation, less workload and good seismic performance.
(6) The combined house is an environment-friendly building, and there is no construction waste during construction.
(7) Flexible business model, which can be sold or rented to provide users with a variety of choices and services.
Due to the above advantages, light steel structure composite houses are widely used in construction engineering, railway and highway construction, petrochemical industry, water conservancy construction, military engineering and temporary buildings in earthquake relief, as well as temporary office buildings, temporary dormitories and temporary small factory warehouses. Shops, newsrooms, restaurants, telephone halls and other commercial buildings; Tourist buildings such as holiday houses; Traffic facilities such as traffic halls, toll stations and sanitation buildings have also been widely used.
There is a great demand for temporary construction in the construction market alone. With the country's regulation of the temporary housing market, the process of replacing other types of temporary housing with detachable combined housing will be greatly accelerated. The detachable mobile house will usher in its golden age of development in the next few years. In addition, due to rising labor costs, the demand for box-type housing will gradually increase. At the same time, the application of box-type combined houses in tourism market and other fields will also expand.
2). Development and application of light steel structure composite residence.
In 1980s, all kinds of temporary houses began to rise. After more than 20 years, temporary housing has developed rapidly, forming cement prefabricated housing represented by Wujiang and Langfang, light steel prefabricated housing represented by Yazhi Company, Rongdong and Chengdong, mobile box-type housing represented by three rivers and mountains, automobile-style housing represented by Zhongtian RV, and tourist villa represented by Baosteel Cai Gang Development Company. Thousands of enterprises have entered the mobile home industry.
Yazhi Integrated Housing Co., Ltd. is a joint-stock enterprise controlled by Shenzhen China Nanshan Development (Group) Co., Ltd., with a registered capital of 654.38+35 million yuan and a total investment of 700 million yuan. The company is committed to the development and management of new integrated houses, advocates the standardization, modularization and generalization of temporary building design and application, and realizes factory mass production. Elegant integrated house has the advantages of energy saving, environmental protection, easy disassembly and reusability, and is a new industry that leads the veneer industry to develop into efficient, environmentally friendly and economical industrialized products and supporting services. The company is headquartered in Shenzhen High-tech Park, with regional headquarters in Beijing, Shanghai, Fuzhou, Wuhan and Chengdu, and supporting large-scale production and distribution bases. The annual production capacity reaches 5 million square meters, and the sales service network covers dozens of key cities across the country, forming a national business pattern. Our products have been exported to Southeast Asia, the Middle East, Africa, South America and other regions. The company has become a manufacturer of production planning, production, sales and leasing of light steel structure combined houses in China. In 2006, the sales reached 654.38 billion yuan, and the construction area was more than 3 million square meters. In 2007, the sales will reach 654.38+04 billion yuan, and the construction area will be about 4 million square meters. The company's light steel structure composite houses have been widely used in the temporary buildings of Beijing Olympic venues, Guangzhou subway and Chengdu new projects.
Rongdong Mobile Home Co., Ltd. was established by Fuzhou No.1 Construction Engineering Company and Japan Donghai Leasing Co., Ltd. in 1988. It introduced the advanced technology and equipment of Japanese modular houses and set up branches and factories in Zhangzhou, Beijing, Shanghai and Xi 'an with a registered capital of 1 100 million yuan. At present, it is a mobile home company with large registered capital, many outlets, high technical level and strong strength. In 2006, the output value was 65.438+0.5 billion yuan. Its houses are widely used in Fujian coastal areas, Beijing, Shanghai, Northwest China and other places.
Beijing Chengdong Housing Manufacturing Co., Ltd. is the earliest professional manufacturer of mobile homes in China. The company has strong R&D capability, advanced technology and high per capita production efficiency. Products are sold to more than a dozen overseas countries, and it is one of the enterprises with foreign trade export performance in the domestic mobile housing industry. It has been widely used in the military parade training room of the 50th anniversary of the founding of the People's Republic of China in Beijing, Xiaotangshan Emergency Hospital and temporary buildings built on the Qinghai-Tibet Railway, and its quality has been well received. Sales in 2006 reached 65.438+600 million yuan, and sales in 2007 will reach 220 million yuan.
3). Market demand forecast of light steel structure composite residence.
The development of domestic temporary housing market in recent five years shows that its market capacity and market maturity are directly proportional to the overall local economic development level. According to the relevant information, the demand for five young temporary buildings with steel structure in the construction industry in the future is as follows: (predict the total demand area of temporary buildings in the construction industry according to the area of 2 square meters per construction worker)
note:
(1). According to the national 11th Five-Year Plan and the 20 10 long-term plan, the average growth rate of the construction industry is 7.5%;
(2) Through the detailed market research in several major areas of China in 2006 and early 2007, due to the stricter requirements for temporary buildings in various areas, the price of mobile homes has been further reduced, and the utilization rate of mobile homes has been further improved in the past two years. A preliminary understanding of the utilization rate of light steel prefabricated houses in various regions is as follows: the utilization rate of board houses in South China represented by Guangzhou and Shenzhen is 65%, that in East China represented by Shanghai is 40%, and that in Beijing and Tianjin is 40%. It can be seen that the utilization rate of light steel mobile homes in economically developed areas centered on the Yangtze River Delta, Pearl River Delta and Beijing-Tianjin region is over 40%, while the utilization rate of light steel mobile homes in economically underdeveloped areas in the west is low. Therefore, the comprehensive utilization rate of light steel prefabricated houses in existing major regions (including South China, East China, North China, Northwest China, Southwest China, Central China and Northeast China) should be around 30%. In order to predict the market in the next five years more conveniently, we set the utilization rate of young steel mobile homes at 30% in 2007, and set the growth rate of light steel mobile homes in the national market at 5% in the first three years and 4% in the second two years, so that we can get the demand area of mobile boards in the next five years. 2. Research and application of light steel structure composite residence abroad.
In the United States, Europe, Japan and other places, light steel structure composite houses have been widely used, and there are many professional manufacturers of light steel structure composite houses, some of which are still very large.
1). ALGECO France is a light steel structure combined house sales and leasing company in France and even Europe. It has factories and branches all over France, dozens of warehouses and more than 6,543,800 square meters of housing inventory. Adequate housing inventory and huge transport fleet ensure the rapid construction and use of housing, thus obtaining good economic and social benefits.
The light steel structure composite residence of ALGECO Company in France is a 1~3-storey residence composed of box units. The interior of the room can be composed of several boxes, or it can be divided into small rooms with light boards. Combined houses can be equipped with balconies, outdoor stairs or indoor stairs. The single-box unit is a base composed of light H-beam, channel steel and square steel tube. Columns and longitudinal beams are made of cold-formed thin-walled steel with special shapes; The roof adopts colored profiled steel plate, thermal insulation material and color steel ceiling plate; The wall panel adopts color steel sandwich panel. The design of column section considers the downpipe and electric wire. ALGECO company has developed a variety of product series according to customer's requirements, such as 1000 series for single economic combination room; The 3000 series is a combination house that can be stacked; 7000 series is a new type of combined housing with box units, which can be divided into 1 1 type according to the size of a single box unit, of which the width is 2.44 m and 2.93 m; There are two kinds of heights: 2.65 meters and 2.84 meters; There are five lengths: 4.40m, 6.2 1m, 7.35m, 8.82m,11.87m; The light steel structure composite houses in ALGECO, France are widely used in various temporary offices, accommodations, hospitals, classrooms, gymnasiums and warehouses. Used in canteens, newsstands, ticket offices and other commercial buildings; Special rooms such as toilets and security guards; It can be used for all kinds of emergency rescue and disaster relief, and can also be decorated inside and outside according to customers' requirements to build high-grade combined houses.
2) There are many professional manufacturers of light-weight steel composite houses in Japan, among which NAGAWA Company is the first manufacturer in the industry to produce, sell and lease light-weight steel composite houses with box unit system. Japan Donghai Leasing Co., Ltd. is a manufacturer specializing in the production, sales and leasing of light steel structure composite houses with box units and frame support systems. 1988 entered China and invested in Fujian, Shanghai, Beijing, Xi and Dongguan successively.
(1). The sales volume of light steel structure residential buildings of NAGAWA Company in Japan reaches 20 1 100 million yen, and there are 22 factories, 47 business halls, 2,300 agency shops and 57 permanent exhibition halls in China. There are three main types of compound houses of NAGAWA Company in Japan:
(1) Single-box units: there are six kinds of box units with different sizes and specifications, which can be assembled into various single-story and two-story combined houses;
(b) Integrated house with box-type structure: the standard box-type units are 5.4m, 5.6m and 7.2m in length, 2.33m in width and 2.697m in height. The standard box-type units are used at the end and middle of the house, with doors and windows, cabinets and toilets, and internal and external stairs. Unified specification for roof, external wall, ceiling, floor, doors, windows and electrical appliances of combined houses. Eight TEU units can form a single-storey and two-storey combined house with various functions.
(3) High-grade combination room designed and processed according to customer's requirements: the structure of the combination room is still a box unit, and only high-grade products are used for indoor and outdoor decoration, cabinets and toilets, and single-storey and two-storey combination rooms can be provided. The combined rooms of NAGAWA Company in Japan are widely used in temporary offices, offices, simple warehouses and storage rooms on construction sites. Various simple shops for holding large-scale activities; Temporary housing for typhoon and earthquake relief. High-grade combined houses are widely used in tourist holiday houses, offices and shops.
The combined house of NAGAWA Company in Japan has the following advantages: on-site installation is quick and simple for 30 minutes, and it can be completed in a complicated day; Modular houses can be dismantled and moved, and the transportation is not affected by rain and snow, which is fast and economical. The rich and novel appearance of combined houses can meet the needs of different customers. The light steel structure composite building has good seismic and wind resistance, high strength and durability. The composite building of NAGAWA Company in Japan has passed the performance and quality certification of ISO900 1 standard for more than 30 years. The compound house is the first in the Japanese industry, and the company is a listed company, so it is favored by customers.
(2) The assembled light steel structure composite building of Japan Donghai Industry Co., Ltd. can be made into a 1~3-storey building, and the structural type is a box structure or a frame supporting structure.
(a) Box-type unit structure system: the columns of the box-type unit are made of square steel tubes, and the beams are made of light H-beams, channel steel and cold-formed steel. The roof and walls are made of sandwich panels. According to customers' requirements, design standard container units of various sizes, such as 5.7 meters long, 2.33 meters wide and 2.698 meters high. In addition, according to the distance, transportation conditions, freight and other factors, the box unit can be made into integral and folding. One is a box. One is the folding box unit structure, that is, the top and both ends of the box unit are processed to be foldable, and the bottom, side plates, doors and windows and other accessories are prefabricated. Because a truck can transport 3-4 box units on top of each other, the freight is greatly saved, and the workload of on-site assembly is not great.
According to the different requirements of customers, the box-type unit structure can form a single-story single building and a horizontal and vertical combined residence; A two-story horizontal and vertical combination house with various internal and external stairs.
(b) Frame-supported structure system: modular building is standardized, and the modulus in both the length direction and the width (span) direction is k,1k =1820mm; P is taken as the modulus in the height direction, 1P=895mm (wallboard width). The dimensions in the length and width direction are all multiples of the modulus K= 1820mm except at both ends. Width: 1.5K=2805mm, 2K=37 15mm, 2.5K=4625mm, 3K=5535mm, 4K=7355mm, 5K=9 175mm. The cornice heights of single-story combined residence are 2640mm(2.5P), 3085mm(3P), 3535mm(3.5P) and 3980mm(4P) respectively, and the cornice heights of two-story combined residence are 5325mm(5.5P), 5770mm(6P) and 6665mm(7P) respectively. Can also provide non-standard specifications of the combined room according to customer requirements.
The columns of the composite room adopt 2C or 3C cold-formed thin-walled steel composite sections; The combined house can be a double-slope roof or a single-slope flat roof. The triangular roof truss of double slope roof adopts cold-formed thin-walled steel, and the flat roof of single slope can adopt 2C cold-formed thin-walled steel I-beam or light welded H-beam. The floor truss beam also adopts C-shaped cold-formed thin-walled steel, and various construction methods can be selected for the roof and wall according to the needs and costs. The roof can be made of two layers of colored profiled steel plates with glass wool in the middle or sandwich panels, and the wall surface can be made of sandwich panels. Doors and windows adopt aluminum alloy doors and windows. 3. Problems in application and suggestions for improvement.
(1). Standardize the market, strengthen quality management, and ensure the safe use of houses.
As mentioned above, the demand for temporary buildings is large and increasing year by year, which is a considerable market. However, at present, the domestic overlay market is chaotic, the quality of houses is mixed, and safety and quality accidents often occur. Some temporary buildings suddenly collapsed in use, some were blown down by the wind, some were burned by fire, some collapsed during installation or demolition, and so on. , causing casualties and property losses, so it is urgent to ensure the safe use of temporary buildings.
The practical experience at home and abroad proves that the light steel structure composite residence is a promising new technology and product. However, due to its short application time in China, it lacks management in terms of design standards and processing quality, and there are also some problems in use, such as roof leakage, corrosion of steel components with low processing and installation quality such as columns, beams and roof trusses, and fire prevention. These problems are closely related to the nonstandard design and processing of light steel structure composite residence.
(2) Solve the design basis and product standards as soon as possible.
Light steel structure composite building is a temporary building. According to the national standard "Unified Standard for Reliability Design of Building Structures" (GB50068-200 1), the design service life of composite buildings is 5 years. Within the specified design service life, the structure should meet the functional requirements of safety, applicability and durability. In order to ensure the reliability of the building structure, in addition to the necessary design and calculation, the material performance, construction quality, use and maintenance should be dealt with. Specific control requirements shall comply with the special provisions of relevant design and construction standards. At present, there is no special standard, specification and reference atlas of light steel structure composite houses for temporary buildings in China. If it is examined and approved in strict accordance with the existing codes and regulations, its design and structure are mostly unqualified, especially for three-story houses. At present, the design of such houses is random or lacking, and the quality of products is difficult to guarantee in the chaotic market. Only the Beijing Municipal Construction Committee has compiled the Technical Specification for Temporary Buildings on Construction Sites (Light Steel Structure) DBJ0 1-98-2005 and the movable mobile home CAS 154-2007 of China Standardization Association. Both of these standards need to be improved, but the modular houses in most parts of China are still in the state of unattended temporary buildings, so they collapse in use. Therefore, in order to meet the requirements of domestic use and export, it is necessary to organize the compilation of the product standards and standard atlas of light steel structure combined houses of the Ministry of Construction as soon as possible.
(3) Discussion on fire protection of light steel structure composite buildings.
The fire protection of light steel structure composite residence should also comply with the national standard Code for Fire Protection Design of Buildings (GBJ 16-87(200 1 Edition). The light steel structure composite building is a temporary building, which can be in accordance with Article 5. 1. 1 of the Code. The fire resistance rating is Grade 4, and the maximum number of layers is 2. The length of the fire zone is 60m, and the building area of each floor is 600m2. Remarks Schools, canteens, vegetable markets, nurseries, kindergartens, hospitals, etc. shall not exceed one floor. In addition, according to Table 2.0. 1 in Article 2.0. 1 of the Code, the combustion performance and fire resistance limit of the components of a building with a fire resistance rating of four are as follows: the multi-layer column is fire resistant, the fire resistance limit is 0.5 hours, and the single-layer column can be combustible; The beam is difficult to burn, 0.5 hours; The floor is difficult to burn, 0.25 hours; Roof load-bearing components, evacuation stairs and ceilings are all combustion bodies; Wall: Non-load-bearing external wall, partition walls on both sides of evacuation walkway, room partition walls are incombustible, 0.25 hours. According to this regulation, the current three-story light steel structure composite residence does not meet the fire protection requirements; Individual schools and canteens have more than one floor; The fire resistance limit of steel columns and beams without roof in two-story and three-story combined buildings can not meet the requirement of 0.5 hour; Everything else can meet the requirements. For this reason, can the steel columns of the two-story combined house be treated with fire prevention, such as coating with fire retardant paint or covering with fire retardant board? In addition, it is necessary to strictly abide by the regulations that the allowable length of the fire zone is 60 meters and the allowable building area of each floor is 600 square meters, and the distance between evacuation stairs cannot be reduced at will in order to save lines.
(4) Actively develop the research and development of light steel structure composite housing.
On the basis of studying foreign advanced technology, combined with China's specific situation, research and develop a series of products suitable for different regions and industries, improve the standardization, finalization and factory level of light steel structure composite housing, and ensure the quality of housing. In addition, the flexible management that can be rented and sold conforms to the civilized construction policy of energy saving and emission reduction, and is also worth popularizing.