Science Popularizing：The history and development of prefabricated building

/in /by

Prefabricated construction is based on component factory production, site for the installation of pattern, fabricated in a standardized design, factory production, assembly, construction, decorate integration and information management, integration from research and development design, manufacturing, field assembly, and other business areas, realization of building products and energy saving, environmental protection and the sustainable development of the whole cycle value maximization of the new building mode of production.

The term assembly was first used in the field of machinery. It refers to the process of assembling parts according to specified technical requirements and making them qualified products after debugging and inspection. Simply put, it is the process of assembling parts into a whole.

In the field of architecture, prefab architecture can be simply understood as a building in which the various parts of a building are directly assembled on site. The most basic components of a building, ranging from the Shanghai Center to the Burj Khalifa to the two-story house handed down from one’s ancestors, are nothing more than the following main parts: foundation, columns, beams, floors and stairs. To realize the on-site assembly of building components, the premise is that these components must be manufactured in advance in the factory, referred to as prefabrication. So in many cases, prefabricated buildings are also called prefabricated buildings or industrial buildings.

At the present stage, assembly-type technology has made obvious progress compared with the previous stage, which is mainly reflected in the following aspects:

Prefabricated building

1. Progress of design concept

In the last century

（1）The effect of joints on the stiffness of prefabricated concrete structures is acknowledged and there are many deductions in the calculation;

（2）Emphasis on full assembly to minimize wet work on site;

（3）By emphasizing the regular arrangement of the walls to realize the overall performance of the structure, the diversification of the building is greatly limited, and the body shape and facade are simplified;

（4）Only applicable to residential buildings with small rooms;

（5）There was no emphasis on industrializing parts.

At this stage

（1）The prefabricated concrete structure is equivalent to cast-in-place concrete, and the calculation diagram is basically the same as that of cast-in-place concrete;

（2）The combination of prefabrication and cast-in-place is emphasized, and the overall performance of the assembled structure is paid more attention to;

（3）On the basis of standardization, the diversity of the building is realized through reasonable structural construction, and changes of facing material and texture. Less restrictions on architects

Suitable for both residential and public buildings;

（4）The industrialization of parts was emphasized.

2. Progress of materials and construction tools

In the last century

（1）The multi-storey building USES reinforced concrete wallboard, while the high-rise building USES reinforced concrete wallboard;

（2）The vertical connection of the reinforced bar in the horizontal joint mainly depends on the lap welding in the reserved pin key;

（3）The horizontal steel bars in the vertical joints are mainly connected by pin keys and steel anchor rings, with only a small amount of cast-in-place concrete at the joints, without the requirement of edge members;

（4）The interface of the joint is smooth;

（5）The floor is made of fully prefabricated large slabs.

At this stage

（1）Reinforced concrete wallboard is required for all;

（2）The vertical connection of the stressed reinforcement in the horizontal joint mainly depends on the grouting sleeve;

（3）The horizontal steel bar in the vertical joint is connected with pin key and anchor ring, and the requirement of edge member is added according to the seismic code；

（4）Joint interface for smooth surface to increase shear rough surface requirements;

（5）It is recommended to adopt composite floor with truss reinforcement or concrete rib.

3. Realize the progress of design technology and construction technology

In the last century

（1）The design technique of handicraft industry;

（2）Industrial operation mode of factory production line;

（3）The maximum tonnage of the crane is small;

（4）Employing 5,000 people – more than 200,000 square meters

At this stage

（1）Introduction of BIM technology;

（2）Introduction of robot and computer control programs on factory production lines；

（3）Maximum tonnage of crane 2000T-m;

（4）Employing 100 people – more than 200 thousand square meters.