2
. 
b
. 
See example a and B
. 
1
. 
The preliminary design of prefabricated building structure according to the policy requirements, the projects using prefabricated construction need to carry out the industrialization implementation plan special report
. 
Information design (BIM)
. 
The key point to realize standardization is the scientific separation of prefabricated components; therefore, the scientific separation of prefabricated components is the core work of prefabricated building structure design
. 
A-1 the length of corner wall is too small (corner window) A-2 the length of wall between windows is too small B ﹣ the net width of plane notch is too small 5
. 
Focus on the following points: A
. 
The splicing parts on both sides of the wallboard should be located in the parts with less structural stress; the vertical prefabricated components should be in the shape of one line first, and the L-shaped, T-shaped, U-shaped and other three-dimensional components should not be used
. 
5
. 
b
. 
Scientific and effective technology combination is adopted to do a good job in collaborative design and control the assembly rate
. 
General description of structural design, including special description of fabricated structural design
. 
c
. 
Table 2.1 key contents of prefabricated component splitting 4
.
The standard has made clear evaluation methods and bottom line requirements for prefabricated buildings
.
whether the length of corner wall and window wall meets the requirements of prefabricated implementation
.
Typical connection details of prefabricated components
.
The detail drawing of components shall include: A
.
Determine the floor number of cast-in-place at the bottom of the building
.
The form of prefabricated components should be simple to control the cost
.
According to the requirements of the standard, “only horizontal prefabricated components and not vertical prefabricated components can not be called prefabricated buildings”, which has the greatest impact on the current prefabricated buildings
.
Calculation sheet of structure specialty, including calculation of vertical component prefabrication rate (volume rate), horizontal component prefabrication rate (area rate), etc
.
the shear wall at the bottom of the high-rise shear wall structure should be cast-in-place concrete
.
Contents of preliminary design drawings of structure specialty: A
.
After entering 2018, another heavyweight document of prefabricated building, prefabricated building rating standard (GB / t51129-2017), has been issued and implemented
.
In the past few years, prefabricated horizontal members have been widely used in prefabricated buildings, and the technology is relatively mature; while prefabricated vertical members are rarely used in prefabricated buildings, and the engineering experience is relatively lacking
.
Structural layout
.
The applicable height of the structure
.
b
.
b
.
The following points should be focused on in the preliminary design stage of prefabricated buildings
.
Therefore, it is necessary to confirm whether BIM is adopted in the preliminary design stage of prefabricated buildings
.
The joint design and construction of horizontal and vertical joints of prefabricated wall panels are the key and difficult points of prefabricated structure, and the performance of joint is the key to ensure the performance of prefabricated structure
.
The content of the report document is basically consistent with the depth of the preliminary design, so the preliminary design can effectively improve the subsequent construction drawing design cycle
.
3
.
The specific rule judgment shall be carried out in accordance with the provisions of code for seismic design of buildings (GB 50011)
.
Detail drawing and processing drawing of prefabricated components
.
Taking the most common shear wall structure as an example, this paper summarizes the key work of structural design in each stage in the design process of prefabricated buildings with prefabricated vertical members
.
Scientific splitting of prefabricated components will have an impact on building function, building plane and facade, structural stress, bearing capacity of prefabricated components and project cost
.
The maximum height of the house with the assembled integral shear wall structure is lower than that of the cast-in-place shear wall structure to a certain extent
.
Disassembly of prefabricated components
.
The layout plan and reinforcement drawing of each floor structure shall be provided; the number of prefabricated components, the number of cast-in-place wall limb, the number of cast-in-place node, etc
.
3、 The construction drawing design of prefabricated building structure should include the following aspects
.
4
.
Joint design should focus on the following points: A
.
The feasibility of using prefabricated components
.
See Table 1.1 for the specific comparison
.
In addition, some cities have mandatory BIM requirements for prefabricated buildings
.
1、 Compared with the traditional cast-in-place shear wall structure, the prefabricated shear wall structure has two remarkable characteristics: first, the cost increment is large (when using prefabricated components, the weighted comprehensive unit price of various types of reinforced concrete components is about three times of the cast-in-place components); second, the feasibility of using prefabricated components should be considered in the layout of structural walls
.
The following points should be paid attention to in the scheme design stage of prefabricated shear wall structure
.
d
.
3
.
Component reinforcement drawing: the longitudinal section indicates the reinforcement form, stirrup diameter and spacing; when the reinforcement is complex, the non prestressed reinforcement should be separated and drawn; the cross section indicates the section size, reinforcement specification, location, quantity, etc
.
b
.
According to the relevant provisions in the technical specification for prefabricated concrete structures: a
.
The structural plan shall include the structural plan of each floor and the roof structure plan; the number of prefabricated components shall be indicated, and the corresponding relationship between the number and model of prefabricated components shall be given, including the weight of components, etc
.
sleeve connection as the most criticized quality defects of fabricated structure, the design documents should specifically indicate the material properties of reinforcement connection sleeve and grouting material and the requirements of relevant testing and inspection.
.
component template drawing, which shall indicate the template size, reserved hole and embedded parts position, size, embedded parts number, necessary elevation, etc
.
1
.
6
.
How to realize the scientific splitting of prefabricated components, the key contents are shown in Table 2.1
.
c
.
Figure 2.1 the core of the industrialization of prefabricated wallboard is the industrialization of production, and the key of the industrialization of production is the standardization of design
.
The basic modulus is 100 mm (1m = 100 mm), and the expanded modulus should be 2 m, 3 m, 6 m, 9 M
.
4
.
Contents that need to be supplemented
.
The common forms of prefabricated wallboard are shown in Annex 2.1
.
The lateral stiffness of the structure should be gradually uniform
.
The construction quality of connection node is the core of the whole structure construction quality
.
shall be indicated for prefabricated components
.
Source: Ocean design collection
.
Therefore, the prefabricated construction project in the architectural scheme design stage needs the intervention of the structure specialty in advance to analyze the feasibility and economy of the prefabricated construction scheme, so as to avoid the later scheme modification and affect the project development progress
.
1
.
Collaborative design of various disciplines
.
Table 1.1 maximum height (m) applicable to different types of shear wall structures 2
.
Focus on the following points: A
.
The external wall should be flat
.
For the structure with transfer layer, the frame support layer and the adjacent upper layer shall adopt cast-in-place structure
.
The application of Bim in the whole industry chain of prefabricated buildings can not only improve the fine management and intensive operation of the project, but also improve the efficiency of resource use, reduce costs, and improve the quality of engineering design and construction
.
3
.
description of structure design, including assembly design
.
The thickness of precast wall panel section should not be less than 200 mm
.
Modular design is adopted for the building
.
The vertical shape of the structure should be regular and uniform to avoid excessive overhanging and retraction
.
The project should adopt the first mock exam, and the modular unification can reduce the types of prefabricated components and reduce the construction cost effectively
.
When the plane concave depth is large, pay attention to whether the concave width meets the requirements of subsequent construction operation
.
According to the technical points of different specialties, the factors affecting the construction cost, construction progress and construction quality are analyzed
.
2
.
The plane shape of the structure should be simple and regular, the distribution of mass, stiffness and bearing capacity should be uniform, and serious irregular plane layout should not be adopted
.
It is not suitable to use bay windows, and try to avoid three-dimensional prefabricated components
.
Introduction after the release and implementation of the State Council No.71 document “guidance of the general office of the State Council on vigorously developing prefabricated buildings” in 2016, the transformation of traditional construction industry has been irreversible, and prefabricated construction will become an important way of construction industry in the future
.
