Keywords

1 Introduction

In recent years, China’s economic level has improved rapidly. By the end of 2022, China’s urbanization has reached 63.89%, and it is estimated that it will increase to 75% by 2030. With the increase of urbanization rate, the noise, dust, garbage and other factors of traditional construction seriously affect the surrounding environment, which is not in line with the current green development policy implemented in China [1]. However, the prefabricated construction project has the advantages of shorter construction cycle, labor saving, improved building quality and less environmental impact, which conforms to the green development concept promoted in China at the present stage [2]. Prefabricated building has become a new target for the development of China’s construction industry. At present, there are still many obstacles to the development of prefabricated buildings in China, such as immature technology, small scale, poor communication and coordination among various units, imperfect standards and policies, especially high construction costs [3]. As an engineering information management technology, BIM can reduce the cost of assembly construction through the management and transmission of information system. The design, component processing, construction and installation information of prefabricated buildings is refined, and the engineering information system at different stages is systematically managed, [4]. In addition, it can also carry out the cost management of prefabricated construction projects, according to the standardized design of components, manufacturing and large-scale construction. The combination of BIM technology and prefabricated building technology makes cost control more adaptable and accurate [5]. This paper will take the prefabricated construction process as the carrier to analyze the causes of the high cost of prefabricated construction, so as to further explore the use of BIM technology for the whole process cost control of construction projects.

2 BIM Technology for Prefabricated Buildings

2.1 BIM Technology

BIM information technology has the advantages of digitalization, informatization, standardization, collaboration, visualization and simulation functions, which facilitates effective information communication, improves construction speed, and thus reduces construction costs. The application content of BIM mainly involves related aspects such as joint cooperation, product design, virtual construction, construction control, cost control and later operation and maintenance management [6].

Through the use of BIM technology, all participating units facilitate the exchange of project information and resource sharing in the whole process of construction. The relationship between BIM technology and all participating units is shown in Fig. 1 [7]. Use BIM technology to explore potential risk factors and possibilities in the design and construction simulation process. Simulate the actual construction process, so as to timely find problems and make correct evaluation, give specific countermeasures and preventive measures, propose optimization measures to guide the actual construction, and reasonably control project materials, time and cost [8].

Fig. 1.
figure 1

BIM technical information sharing platform

Full size image

2.2 The Development Status of Prefabricated Buildings

The prefabricated building model started earlier in developed countries. At present, the related theories and management systems of prefabricated buildings are more mature. China’s prefabricated construction industry is still in the initial stage of development, and a big gap exists compared with developed countries. Many factors restrict the rapid development of prefabricated construction industry in our country, among which lack of standards, industrial dispersion, small scale and high cost are all existing problems [9]. As the core factor restricting the development of prefabricated building projects, cost-related issues have received extensive attention. Although the state has put forward many favorable policies for the prefabricated construction industry, high construction cost is still one of the main problems restricting the development of the prefabricated construction industry [10]. The design cost, production cost, transportation cost, construction and installation cost of prefabricated construction project are the key to cost management.

3 Analysis of Influencing Factors of Prefabricated Building Cost by BIM Technology

To determine the influencing factors of the cost management of prefabricated building based on BIM technology. Through literature research, combined with the whole process cost management of prefabricated building with BIM technology, this paper finally determines 22 influencing factors in 5 stages (shown in Table 1) that affect the cost of prefabricated building with BIM technology:

Planning and design stage (PD stage):

BIM collaborative design degree (PD1); BIM design standard perfection (PD2); The degree of component splitting design (PD3); Number of design changes (PD4); Assembly rate (PD5); Lack of BIM technical personnel(PD6); (shown in Table 2).

Production and transportation stage (PT stage):

scale and production capacity of component factory (PT1); Types of prefabricated components (PT2); Production quality of prefabricated components (PT3); Mold utilization rate (PT4); Platform degree of access to information(PT5); Component transportation scheme (PT6); (shown in Table 3).

Construction and installation stage (CI stage):

mechanical equipment lifting scheme (CI1); Construction and installation efficiency (CI2); Degree of application of BIM technology (CI3); Field component management (CI4); (shown in Table 4).

Operation and maintenance stage (OM stage):

maintenance of subsidiary works (OM1); Facility maintenance (OM2); Property information management (M3); (shown in Table 5).

The demolition recycling stage (DR stage):

Demolition scheme (DR1); Demolition efficiency (DR2); Component recovery rate (DR3). (shown in Table 6).

In view of the above factors affecting the whole process cost management of BIM prefabricated buildings, the relevant professionals were investigated. The following data is obtained. According to the survey results, AHP hierarchical analysis software is used to complete the formation of the evaluation matrix, and the following table is formed.

Table 1. Project whole-process judgment matrix
Full size table
Table 2. Planning and design stage judgment matrix
Full size table
Table 3. Production and transportation stage judgment matrix
Full size table
Table 4. Construction and installation stage judgment matrix
Full size table
Table 5. Construction and installation stage judgment matrix
Full size table
Table 6. Demolition recycling stage judgment matrix
Full size table

\(\lambda_{\max } = \sum\limits_{i = 1}^n {\frac{(AW)_i }{{nw_i }}}\) is obtained by calculating formula \(\overline{w_i } = \sqrt[n]{{\prod\limits_{j = 1}^n {a_{ij} } }}\). The analytic hierarchy process is used to screen each influencing factor, and the 22 influencing factors affecting the cost of prefabricated building with BIM technology are sorted, and the following results are obtained (Table 7):

Table 7. Weight table of influencing factors
Full size table

4 Application of BIM Technology in the Whole Process Cost Management of Prefabricated Buildings

4.1 Cost Control in the Planning and Design Stage of BIM Technology

Establish Component Family Library.

By using the highly collaborative and drawing optimization characteristics of BIM technology, a standardized component family library is established, which enhances the standardization and universality of components, and realizes the reuse of components. At the same time, the reduction of the apportion cost of mold production greatly reduces the production cost of components.

Collaborative Design.

Each specialty collaborates on the same network platform to share information, which facilitates communication between the participating units, thus reducing cross-specialty communication time and facilitating timely discovery of contradictions in product design, thus reducing unnecessary economic losses caused by later modifications.

Detailed Design.

BIM software is used to complete the component splitting design diagram. Match the visual function of BIM technology, component processing plant can directly use BIM model of split design drawings information standardization production, reducing the error rework probability, which reduces the cost.

4.2 Cost Control in the Production and Transportation Stage of BIM Technology

Improve the Production Quality of Components.

The use of BIM technology can improve the accuracy of component manufacturing. Design changes can also be modified in the model using BIM technology. The information is more accurately and efficiently communicated to the manufacturing personnel, thus reducing the waste of production costs caused by unnecessary errors.

Improve the Utilization Rate of Molds.

According to incomplete statistics, the amortization cost of the mold accounts for about 10% of the entire engineering component processing cost. The use of BIM technology can synchronize the design drawings, optimize and classify various component parameters, and improve the utilization rate of molds. As a result, the production quantity and amortization cost of the mold are reduced, and the cost is effectively controlled.

Optimize the Transportation Plan.

Compared with traditional cast-in-place concrete construction, the cost of transporting components from the processing plant to the construction site is significantly increased, which is also a key link to reduce transportation costs. Through simulation technology, the optimal type and number of transport vehicles are selected to reduce the number of transport. The mileage, traffic quality, road conditions and other information of different transportation routes are input into the BIM technology information management platform, and the BIM technology is used to simulate the transportation process and select the best transportation route, so as to improve transportation efficiency. In addition, BIM simulation function is used to simulate the installation sequence of components, and a transportation route that can be effectively combined with on-site installation and construction is established to increase the full load and reduce the cost.

4.3 Cost Control in the Construction and Installation Phase of BIM Technology

Improve the Efficiency of Construction and Installation.

The construction organization scheme of prefabricated buildings is simulated by using BIM technology to simulate the advantages of construction. In the process, the construction organization plan and layout plan were optimized. Set up places properly such as tower cranes and construction components, optimize temporary construction road, vehicle transport road route. Minimize the secondary handling of building materials and machinery, reduce the production cost of the project in the construction process, and improve the hoisting efficiency and installation efficiency of construction machinery.

Optimize Component Management.

BIM technology determines the pre-construction plan and the phased purchase quantity of components according to the on-site data analysis. According to the actual needs of construction site progress, the requirement of prefabricated components in each installation and construction stage can be quickly calculated. Thus, the practical problems such as secondary handling of components and material accumulation exceeding the limit are solved. In addition, if the construction plan needs to be changed during the construction process, BIM technology can also be used to detect the construction status of the site, so as to effectively adjust the approach arrangement of the components to meet the needs of the installation of various parts.

Improve the Installation Technology Level.

During the construction and installation of prefabricated buildings, the workload of vertical transportation is relatively large. Currently, it is faced with the problem that the construction and installation technicians lack experience and can not fully grasp and skillfully use the lifting skills of prefabricated components. After the disclosure of 3D visualization construction technology, the visualization characteristics of BIM technology are used to simulate construction and dynamic demonstration of component layout. Construction and installation project management personnel can quickly master the construction technology, understand the technical difficulties and key nodes in construction and installation in advance, and formulate corresponding measures in time. It greatly improves the construction efficiency of construction engineering and the accuracy of installation management, and effectively reduces the cost of construction engineering in the construction process.

4.4 Cost Control in the Operation and Maintenance Stage of BIM Technology

Maintenance of Subsidiary Works.

The use of BIM technology can more directly view the type of materials used in the damaged location, specifications and sizes, steel bar diameter, and the relevant information of its suppliers, making the maintenance process more simple and effective, greatly improving the service level in the operation and maintenance stage, thereby reducing unnecessary cost losses.

Property Information Management.

BIM technology is used to establish BIM property management system, so that managers can grasp the latest equipment and facilities operation status in the first time. Moreover, by increasing the number of equipment and facilities for the property or operator, the management unit can also meet the operation needs with the optimal cost management on the premise of ensuring the quality and use efficiency of the prefabricated building.

4.5 Cost Control in the Operation and Maintenance Stage of BIM Technology

Optimize the Demolition Scheme.

At present, due to the lack of demolition and recycling in domestic prefabricated construction projects, the experience of demolition and recycling is not perfect. At the same time, the level and technology of demolition of traditional cast-in-place concrete buildings in China are also relatively backward, and the formulation of demolition scheme at this stage is the difficulty of construction. However, the input of the demolition plan of the prefabricated building into the BIM model can improve the database of the whole process of the prefabricated building, which provide a certain reference for the formulation of the demolition and recycling plan in the later stage.

Improve the Demolition Efficiency.

The structure of prefabricated buildings is more complex than that of traditional cast-in-place buildings, so the difficulty of demolition is also greater than that of traditional buildings. If only this simple and rough demolition method of machinery is used, it will not only cost more, but also take a longer time. The actual demolition work is input into the BIM model, and the simulated construction can be carried out in the model first. This can predict various risks in demolition and solve them in advance, significantly improve the efficiency of demolition, and reduce the cost of demolition, thus minimizing economic losses.

Improve the Recycling Rate of Components.

When BIM technology is used to dismantle prefabricated buildings, the BIM model can sort out and classify recyclable components, realize resource recovery and utilization, and improve the rate of return.

5 Conclusions

The high construction cost of prefabricated buildings is one of the key factors that hinder the promotion of prefabricated buildings. At the same time, due to the development of science and technology and the change of management mode, China’s construction industry is also constantly transforming and upgrading, towards the development goal of environmental protection, industrialization and information technology. In this paper, the whole process cost management of prefabricated building based on BIM technology is deeply studied, the cost management effect of BIM technology in the whole process of prefabricated building is analyzed, and the cost management methods and suggestions for the five stages of prefabricated building cost management are given.