Off-site construction has gradually become industry-accepted with different building elements manufactured and pre-installed in off-site factories, and its full lifecycle can be divided into design, production and prefabrication stages. To enhance data interoperability and facilitate full lifecycle of off-site construction, processing building data for design model and the following digital information transformation play an essential role in guaranteeing seamless communication. However, there are three major limitations while facilitating full lifecycle of off-site construction: (1) a lack of an integrated design collaboration method to underpin the data interoperability as well as the efficiency of information processing and ensure the traceability of design changes for prefabrication...[ Read more ]

Off-site construction has gradually become industry-accepted with different building elements manufactured and pre-installed in off-site factories, and its full lifecycle can be divided into design, production and prefabrication stages. To enhance data interoperability and facilitate full lifecycle of off-site construction, processing building data for design model and the following digital information transformation play an essential role in guaranteeing seamless communication. However, there are three major limitations while facilitating full lifecycle of off-site construction: (1) a lack of an integrated design collaboration method to underpin the data interoperability as well as the efficiency of information processing and ensure the traceability of design changes for prefabrication, (2) a lack of a methodology utilizing standardized data models and process to increase the level of digitalization and automation of production management, and (3) a lack of an integrated workflow and corresponding data models relating to data integration to represent prefab-related working process for prefabrication automation. To tackle these limitations, this research develops an integrated approach that can achieve productive and efficient data transformation from design, production to prefabrication stage.

This research firstly presents an approach with the aid of Building Information Modeling (BIM) and blockchain technologies for collaborative design and prefabrication in Modular Integrated Construction (MiC). The integration starts with the information processing including extension of Industry Foundation Classes (IFC) and BIM Collaboration Format (BCF), which are openBIM standards and can provide an open environment for construction practitioners and enhance the level of digitalization [26]. This involves the extension of prefab-related information, on which a proposed module-identification algorithm is applied to provide higher efficiency for information extraction and processing. Next, a change detection algorithm is established to automatically resolve clashes caused by simultaneous work in design collaboration, and the detected changes are recorded by a proposed blockchain network for better traceability and immutability of design information among different stakeholders due to the unique characteristics of blockchain technology. The proposed framework is demonstrated with JupyterLab and Hyperledger Fabric in illustrative examples, the results of which indicate that the proposed algorithms and blockchain network outperform conventional approaches in the efficiency of information processing and tracking.

The level of digitalization in the construction industry is always falling behind than in other industries, and the information flow in production management along the full lifecycle of the off-site construction industry encounters more unexpected obstacles than in the traditional production mode [10]. Consequently, this research then proposes a blockchain-enabled approach utilizing openBIM standards to encourage BIM adoption so as to increase the level of digitalization and automation. The approach consists of two major parts: the data contract and the data escrow systems, which starts with the development of a standardized object-oriented database as the foundation of the main parts, utilizing openBIM standards including IFC and buildingSMART Data Dictionary (bsDD). As one of the main parts, the data contract consists of an Information Delivery Specification (IDS)-based asynchronous workflow and a post-project evaluation system, which includes related grading metrics and Model View Definition (MVD) for future reference. The other major part, the data escrow system, utilizes blockchain as the underlying engine and a PaaS (Platform-as-a-Service) platform is proposed to increase its scalability and flexibility. In the illustrative examples, a BIM model was used to demonstrate the file-based information exchange and adopted openBIM standards as well as their related data models, which streamlines and visualizes the approach in utilizing different openBIM standards in terms of data, workflow standards and data tools. The successful implementation of the blockchain-enabled PaaS application showed that the mechanism of the approach functions well.

When moving towards the construction automation, off-site prefabrication is important with the aid of BIM and IFC which are utilized as a collaborative approach to facilitate the fabrication workflow and data interoperability. This research presents the integration of BIM and fabrication machine codes with openBIM standards to interoperate the computerized design and prefabrication automation. BundesVereinigung der Bausoftware (BVBS) is utilized in this research since steel reinforcement is demonstrated in this research as the example. The integration begins with the reference of IDM which involves the identification of information requirement in the process map for identifying the necessary data exchange within the prefabrication process. Definition of IFC model views is conducted to ensure that the exchange of data meets the end user’s needs and is implementable for software applications. Next, the process information model of steel reinforcement fabrication is established by connecting the IFC entities with relationships among the specific tasks. A new approach is developed to extend the IFC data schema with prefab-related entities. The proposed BIM-BVBS integration is demonstrated utilizing IFC viewers and visual programming tools (Dynamo) in illustrative examples, the results of which reveal that prefab-related entities and attributes in IFC-based BIM models can be extracted efficiently to cater to the BVBS data transformation toward automatic prefabrication.

This research develops an integrated approach that can achieve productive and efficient data transformation through the full lifecycle of off-site construction while enhancing the data interoperability and largely increase the level of digitalization. This approach has been implemented and validated, proving that its performance outperforms conventional ones.