by In recent years, under the background of the country’s vigorous promotion of green development, transformation and upgrading and supply-side reform, prefabricated buildings have received widespread attention, and many provinces and cities have successively issued policies to support the development of relevant construction industries.
Shenzhen, in Guangdong Province, took the lead in introducing relevant preferential policies and relevant implementation rules, promoted the construction of several pilot demonstration projects in two years, and also vigorously promoted prefabricated buildings in the area of government-subsidized housing, forming a good situation in which real estate developers paid attention, and design units, component manufacturers and construction units responded positively.
Prefabricated concrete buildings use a large number of prefabricated components that are processed and manufactured in the factory in advance, and carry out assembly construction on the site, which has the advantages of saving labor, overcoming the influence of weather, and facilitating perennial construction.
Adopt the integrated design and construction of architecture and decoration.
The ideal state is that the decoration can be carried out simultaneously with the main body construction, and its components should meet the requirements of safety and standardization.
The factory operation mode greatly reduces the on-site wet operation, formwork, reinforcement binding operation, scaffolding erection, strong and weak wire box, casing embedding and manual use, which is in line with the current development direction of building energy conservation and environmental protection in China, and is the construction mode vigorously promoted in China at this stage.
In accordance with the relevant national policies, the five-in-one management mode of “design standardization, production industrialization, decoration integration, on-site assembly and whole-process informatization” is widely promoted in prefabricated construction projects.
The higher the degree of standardization of component design, the higher the utilization rate of mold, and the higher the production efficiency of the factory, the lower the corresponding component costs will be, in cooperation with the factory’s digital management, The whole prefabricated building will be more cost-effective.
At present, the biggest confusion is that some practitioners lack the training in the design of prefabricated buildings and the implementation of prefabricated projects, and have no overall concept of the understanding and application of standards, resulting in too many types of components, high costs, confusion in on-site construction management, poor technical and economic performance, and even some quality problems in individual projects.
The author believes that the main reasons for this phenomenon can be analyzed from two aspects: design and management.
The first part of the design section is that the prefabricated design must be selected from the stage of establishing the preliminary design scheme, which is the source of standardized design.
At present, there are some prefabricated schemes that are designed first and then split.
The appearance of this part of prefabricated building components is mainly to respond to the policy requirements, and the original traditional cast-in-place design scheme is changed to prefabricated design scheme.
It is not determined to select prefabricated buildings when the project is approved and formulated.
For these projects, the technical system and technical route should be clarified by adopting the idea of prefabricated building design from the project approval planning document, otherwise, It will be difficult to reach the level of specialization and standardization.
Second, the difficulties and costs of components in production, storage and transportation should be fully considered in the design.
The prefabricated building advocates the factory production of components that are difficult to produce on site.
The implementation of this concept can effectively reduce the construction difficulty on site and improve the construction efficiency.
However, the design should be based on the premise of meeting the structural safety and related functions on site, optimize some complex and weak positions and nodes to reduce the cost of component production and installation.
At present, the development of the prefabricated component industry is still insufficient, and the design institute is lack of professional prefabricated building design talents, resulting in insufficient understanding of the relevant production process of prefabricated components.
The impact of various processes such as production, storage and transportation on the components is not fully considered when designing the components.
The designed components are thin in structure and complex in nodes, resulting in production difficulties, and are prone to fracture under the conditions of demoulding, storage and transportation In order to protect such nodes, mold, storage, transportation and other measures must be added in the factory and construction site, which will inevitably increase costs.
Third, the component installation process, installation difficulty and construction cost should not be fully considered in the component design.
Because some of the designers of prefabricated buildings at this stage are converted from the traditional cast-in-place building designers, the relevant experience is relatively lacking, the structure and installation process of the components are not understood enough, and they are worried that the installation of the components will bring adverse effects on the main body of the building, so a large number of complex nodes should be used in the design, such as a large number of closed hoops or oversized steel bars are applied to the components, but the installation process of the components is not considered, It is difficult to install and bind the reinforcement at the site in the later stage, and even impossible to construct, resulting in the delay of the construction period and the increase of the cost due to the change of the formwork, and also violating the design concept of strong main body and weak components.
Fourth, prefabricated buildings should achieve the main decoration and electromechanical integration.
Integration and integration are important characteristics of prefabricated buildings.
However, to achieve integration and integration, new technical and management requirements are put forward for construction units and design units: technology advancement and management advancement.
In the early stage of component design, it is required to organize the subcontractors of various disciplines such as architecture, structure, water and electricity, interior decoration, and participate in and complete the design of relevant disciplines in advance.
Finally, the design unit will integrate the requirements of various disciplines into the components.
This is a big difference between the prefabricated building construction and the traditional cast-in-place building, and also poses a new challenge to the construction unit and the design unit.
Fifth, the application of BIM technology in prefabricated construction projects should solve practical problems, not only as a means of publicity, but also focus on solving some difficulties in production or installation processes and nodes, and step by step promote the application of BIM.
For the management of site construction, the site manager should be a manager with certain experience who has a deep understanding of prefabricated buildings.
For the management of traditional cast-in-place construction, it is necessary to change the management concept in a timely manner, not stay in the management mode of traditional cast-in-place buildings, but really achieve the technology advancement and management advancement.
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