compared with the traditional cast-in-place concrete assembly project, what does the construction organization design focus on? China's current construction technology was formed in 1981s, that is, cast-in-place reinforced concrete system, also known as wet operation. This construction method solved three major problems at that time: first, the capacity of hoisting equipment was limited; second, the labor force in China was abundant in the early stage of reform and opening up, making it difficult to find employment; and third, the cast-in-place system had good seismic performance. Later, the existing concrete buildings were basically used in building construction, which contributed a lot to the rapid development of urban and rural construction, but the disadvantages were also obvious. First, the construction technology was too extensive and the building materials such as steel and cement were consumed more; Second, the construction site is dirty and messy, which is an important pollution source of urban inhalable particles; Third, the problems such as cracking and leakage of building quality are outstanding, which is also caused by the technology of cast-in-place concrete, and it is the problem that Chinese people complain the most about buildings. Fourth, the current labor force in China is generally insufficient, and the difficulty in recruiting workers has become one of the important problems facing the construction industry. Therefore, the development of prefabricated buildings is the general trend, which is independent of the will of others.

The main features of prefabricated buildings are as follows:

11. Diversified functions

Through a large number of on-site assembly operations, the on-site cast-in-place operations are greatly reduced, which can significantly improve labor productivity. From the functional point of view, first of all, the external wall design of prefabricated buildings has the function of heat preservation, which can make residents feel warm in winter and cool in summer, saving the use times of air conditioners and reducing the air pollution; Secondly, the sealing function of the wall, doors and windows of the assembled building is good and the sound insulation effect is good; Third, it has good fireproof and seismic performance. The special materials of the assembled building can provide people with a safe and comfortable living environment, which is not easy to spontaneously ignite in dry weather, and there will be no problems such as cracks and yellowing after long-term use. The assembled building has good seismic performance.

12, construction and assembly

A large number of components of prefabricated buildings are produced and processed by the factory. The design and construction procedures of building and decoration are integrated, and the decoration can be completed in the factory with the main construction, which not only ensures the decoration quality, but also accelerates the overall progress of the project. Because the assembled building is lighter than the traditional building, people can directly carry out construction on the site as long as they draw the basic structural map. Because of its very fast construction speed, the work efficiency is also improved a lot.

13. Diversification of design

Prefabricated buildings are more in line with the requirements of green buildings, and the standardization of design and informatization of management are higher. With the digital management of factories, the cost performance of the whole prefabricated buildings will be higher and higher. Moreover, at present, the design of buildings is mostly based on the fixed pattern in the room, and the overall use of houses is not very flexible, but the prefabricated buildings can avoid such shortcomings. The main residential leaves are divided into sizes and configured according to the requirements of residents.

14, prefabricated building construction technology

prefabricated building is the main form, product and carrier of building industrialization, which has the characteristics of industrialization, assembly, standardization and integrated decoration. It is an industrialized building assembled by building parts, building components, structural components and electromechanical equipment in a reliable connection way. Assembled concrete structure is the most important structural form of assembly and distribution buildings in China at present.

(1) The main components are prefabricated. A large number of building parts and components are prefabricated by workshop production, and high-precision prefabricated components can be manufactured with error controlled within a few millimeters by using planarization construction method supplemented by advanced computer calculation instead of three-dimensional intersection operation of cast-in-place structures. Based on the strong compatibility of concrete materials, a wide variety of products can be produced by prefabrication industry.

(2) Most prefabricated components adopt an integrated manufacturing process that integrates waterproof, thermal insulation and structural molding performance, thus reducing material loss and construction procedures. At the same time, because the casting, maintenance and storage of prefabricated components are all carried out in the factory, it is less affected by the weather, which is beneficial to winter construction. During the production and storage of the factory, harmful substances in building materials are released, and the assembled building will not cause harm to human body after completion.

(3) After the prefabricated structures and building components are completed, they will be transported to the construction site and assembled by mechanized hoisting. Concurrent engineering can be used in the construction period. While the design institute draws some or all of the component drawings, the prefabricated component manufacturer will manufacture, store, deliver the components, and the pile engineering, foundation and underground engineering construction on site can also be completed at the same time. The hoisting process and prefabricated component production process can be carried out at the same time with the construction of various disciplines on site. In addition, the construction method of assembled building is changed to factory production because it no longer follows the traditional operation surface process, which plays a role in reducing the construction process of operation surface and reducing the construction difficulty, greatly improving the labor efficiency of engineering construction and greatly shortening the engineering construction period.

(4) There are high requirements on the measuring accuracy of setting-out and bidding bureau and the position of reserved holes. Due to factory production, the size of the components cannot be changed after prefabrication. If the pay-off size is too small, the prefabricated components cannot be installed, and if it is too large, the flat-fell seam will be too large. Elevation measurement also needs to be more accurate. If the elevation of shear wall is not well controlled, the composite slab can not be installed smoothly, or the gap between shear wall and slab is too large, so formwork needs to be re-supported. When the prefabricated concrete structure is reserved and embedded, the position and size of the hole must be accurate, otherwise it will increase the difficulty of construction and even affect the safety of the structure.

(5) The construction and installation process of assembled concrete structure is relatively complicated, and its construction process requires higher engineering practice experience, technical level and management ability of employees. At present, the relevant standards and specifications of prefabricated buildings in China obviously lag behind the development of construction technology, which limits the application field of prefabricated buildings and the total height and storey height of buildings.