The prefabricated structure refers to the construction of the building pre-fabricated in advance in the factory or on the construction site or elsewhere, and then the construction of these buildings is transferred to the construction site by means of transportation, through the cooperation of a certain splicing technology and some mechanical lifting, The building structure is constructed by assembling these scattered prefabricated buildings into a whole. With the sustained and rapid development of China's economy, the continuous increase in labor costs, and the increasing awareness of energy conservation and environmental protection, in recent years, China's research on prefabricated structure construction has gradually increased, and many units have developed some technologies. the study. Among them, the representative Vanke enterprise has become a pilot real estate enterprise of prefabricated structure construction in my country, has completed more than ten projects of actual size, and obtained good economic benefits.
1 Classification and advantages of prefabricated structure
1.1 Classification of prefabricated structures
Prefabricated buildings can be divided into two categories according to their degree of assembly:
(1) Fully assembled.
All components of this type of building are just like mechanical production products, which are produced in batches in the factory and then transported to the construction site for assembly. These components mainly include assembled large slabs, beams, frame structures, slab-pillar structures, box structures, etc. The maintenance structure around the fully assembled building can be masonry or pouring on site, as well as prefabricated wall panels. The main advantages of this fully-assembled building are the high production efficiency of building components, the quality of mass-produced components is guaranteed, the construction speed of direct splicing is fast, and the seasonal impact during the construction process is small. Large and relatively stable areas, if factory production of building components will achieve better results.
(2) Semi-assembled type.
The main load-bearing components of such buildings are partly prefabricated components and partly will be built on site. For example, in building structures, brick walls are generally used for vertical load-bearing, so such components can be masonry on site. Like floors, beams. Stair platforms and other horizontally load-bearing components generally use prefabricated components for site hoisting. In large-scale buildings, a common practice is to use prefabricated components for the outer wall, and the inner wall is usually cast-in-place using formwork. The main advantage of this type of construction is that the one-time investment cost of the required production base is less than that of a fully assembled building, the adaptability is more extensive, a large part of the transportation cost is saved, and it is easy to promote. Under certain conditions, it can also achieve the effect of shortening the construction period, which is more conducive to the realization of large-scale flow construction in various places, and can obtain good economic effects and better structural integrity. At present, relatively more semi-assembled structures are used in my country's buildings, which are assembled monolithic structures.
1.2 Advantages of assembled structure
According to foreign statistical data, the advantages of prefabricated buildings were introduced in terms of construction speed, engineering cost, etc.:
(1) Saving labor.
Also according to the data, the average time for a square meter in France is 20 man-hours per square meter, but after using prefabricated buildings for industrial production. After the assembly technology is used in construction, the man-hours per square meter fell to 11.5 man-hours. Obviously, when it was changed to a prefabricated building structure, construction labor savings by nearly 50%. In addition, it also reduces the intensity of labor.
(2) Shorten the construction period.
In Japan, under normal circumstances, a 100-family five-story residential house with a traditional construction method requires a construction period of 240 days. However, prefabricated buildings and building components are pre-fabricated at the factory and carried out on site. After the construction method of mechanical hoisting, it took only 180 days to complete the construction of a five-story residential building of 100 households, which shortened the construction period by 25%.
(3) Reduce the cost.
When the prefabricated structure and industrial construction methods are adopted, the construction cost per square meter is lower than that of the traditional structure. However, due to the different economic conditions of various countries, the structure of the building is also very different, so the cost reduction data are also different.