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Document management systems in AEC projects manage important project documents such as schedules, RFIs, and change orders. Hence, security concerns in document management systems especially involving data integrity of documents and records may have a severe effect on a project in terms of money and the reputations of project participants. Therefore, in this research blockchain technology is leveraged to facilitate data integrity in document management for construction applications through - (1) irreversible and irrevocable approval workflow logic via smart contract technology, (2) irreversible recording of document changes via blockchain ledger technology, and (3) document version history integrity via a blockchain-based data structure. A prototype of the proposed smart contract framework was developed using Hyperledger fabric and evaluated. The scalability of the proposed framework to support document version integrity was also evaluated and discussed. A formulation based on existing literature is developed to evaluate the cost viability of the proposed framework. • A smart contract logic to facilitate integration via customizable document approval workflows is developed. • A data structure to securely record document version history is developed. • A blockchain ledger data model to securely record document lifecycle is developed. • An example scenario and prototype evaluation of the proposed framework are presented. [ABSTRACT FROM AUTHOR]

Existing platforms for collaborative BIM design have a centralized system architecture, which suffers cybersecurity risks of design data manipulation and denial of access, leading to a loss of data traceability, a decline in design productivity, and project delays. Blockchain is a promising technology to solve such risks by providing decentralized and immutable data storage. However, integrating blockchain with BIM faces a problem that blockchain is inherently unsuitable for storing large-sized design files like BIM models, hindering blockchain from protecting BIM data integrity. Therefore, this paper proposes a distributed common data environment (DCDE) framework for BIM-based design leveraging two distributed technologies: blockchain and Interplanetary File System (IPFS). The DCDE framework guarantees irreversible design changes storage using blockchain while secures design file storage using IPFS. A blockchain transaction data model and a smart contract are also developed within the framework to support DCDE functionalities. Lastly, framework applicability and performance are tested in an illustrative design example. Results show that: (1) DCDE is a feasible solution for secure design collaboration, and (2) DCDE latency (in millisecond-level), TPS (60 transactions per second), and storage cost (12.5 KB per day) are within an acceptable range. • A distributed common data environment (DCDE) framework is proposed using blockchain and IPFS technologies. • An original transaction data model compliant with ISO 19650 standards is developed for recording design changes. • A smart contract algorithm is developed for design transactions sharing and querying. • The proposed DCDE framework is deployed in a design example to illustrate its feasibility and performance. • Results show that the proposed DCDE is a promising solution for secure decentralized design collaboration. [ABSTRACT FROM AUTHOR]

Security of information in collaborative BIM platforms is crucial particularly for critical projects such as that of government buildings, prisons, and power plants. Inappropriate distribution and loss of sensitive information may potentially lead to physical security threats, financial loss, and loss of trust and reputation. Therefore, this paper identifies the information security requirements of collaborative BIM platforms considering the characteristics related to data security of collaborative BIM platforms through a literature review and as a result, identifies seven components of BIM security, based on which defines three levels of BIM security. Existing cybersecurity facilitating technologies such as encryption protocols, distributed database technology, and blockchain technology are reviewed to assess applicability to BIM security. This review shows that although the technologies to support BIM security are available in research and on market, they are not customized in existing collaborative BIM platforms to support BIM security. Therefore, two conceptual frameworks are proposed – (1) an encryption strategy-based framework to facilitate secure storage and distribution of BIM and (2) a blockchain-based framework to record BIM changes in a tamper-proof ledger for the non-trusting environment of construction projects. Discussions on cost and functionality are provided, which will be further extended in the future. • A comprehensive study on the requirements of BIM security is presented. • Levels of BIM security are defined with examples. • Existing and emerging cybersecurity technologies were reviewed for BIM security. • A conceptual encryption strategy for securing BIM data distribution is proposed. • A conceptual distributed blockchain-based framework for BIM change recording is proposed. [ABSTRACT FROM AUTHOR]

Interim payment provisions in construction projects are susceptible to unfair practices. In construction project participants with varying financial capacities belonging to different organizations are bound by contractual relationships. Due to this type of project organizational structure, project participants do not completely trust each other which prevents the adoption of existing centralized automated frameworks for interim payment. Therefore, this paper presents a distributed blockchain-based framework that does not require to be trusted for automatically enforcing the terms and conditions related to interim payments and sharing payment records at project-level transparently and securely. A logic to automatically initiate, validate, and disburse interim payments according to general contract conditions for interim payments is formalized in this paper. A blockchain-based data model that enables selective-transparency in payment records is proposed. This data model facilitates the sharing of sensitive financial information privately between two contracting parties and non-sensitive payment-related information publicly among all project participants. The proposed blockchain-based framework is supported by a key management strategy to facilitate different security properties such as confidentiality and authenticity of data and users. Considering the non-technical nature of construction project participants, the proposed key management strategy is designed to dynamically generate cryptographic keys from publicly sharable parameters so that storage and management overheads are reduced. Security properties such as immutability, data confidentiality, user integrity, performance, and cost of deployment of the proposed blockchain framework are validated and recommendations for executing the proposed framework with a high level of security are discussed in this paper. • Automated and secure execution of interim payment via smart contracts is facilitated. • Data model for selectively-transparent recording of payments on blockchain is presented. • A blockchain-based key management strategy for data confidentiality in construction projects is presented. • Cost and security of the framework are evaluated and discussed. [ABSTRACT FROM AUTHOR]

Integrating building information modeling (BIM) with emerging blockchain technology has gained considerable attention in addressing design collaboration problems like poor data security, weak traceability, and low transparency in off-site construction. However, blockchain implementations in off-site construction design, especially with openBIM standards, currently lack standardized workflow management and methods for ensuring data completeness within the blockchain environment. To bridge these gaps, this paper presents a novel blockchain-enabled platform-as-a-service (PaaS), specifically tailored for off-site construction to enhance interoperability and collaborative design efficiency using openBIM standards. The proposed PaaS offers two significant intellectual contributions: (1) a data contract system that manages openBIM workflow standardization and (2) a data escrow system that ensures the completeness and integrity of openBIM data. The data contract system utilizes an innovative asynchronous smart contract algorithm to streamline workflow checks, while the data escrow system introduces a new blockchain-driven data-checking strategy to ensure openBIM completeness at the data level. Besides, a PaaS architecture is developed to clarify the interaction logic between these two systems. The PaaS is validated and evaluated in openBIM-based design collaborations from a real-world project, with results indicating improvements: a 38% time-saving in design issue coordination and a 32% reduction in design data delivery time. Furthermore, the platform received favorable feedback from project participants, validating the approach and confirming the PaaS as a valuable tool for enhancing design collaboration in off-site construction. • Proposed a BIM-based blockchain framework for production management utilizing openBIM standards • Developed a standardized object/process-oriented semantically enriched Asset Information Model (AIM) • Proposed a data contract system with prefab-related data structures for automatic digitalization transformation • Integrated IDS with blockchain to build a transparent and consistent information-sharing strategy • Designed a data escrow system integrating with blockchain technology for openBIM data completeness checking [ABSTRACT FROM AUTHOR]

Blockchain technology has gained increasing attention in the construction sector. The process of developing a blockchain-based application that fits user requirements largely depends on the selection of a suitable consensus protocol, which acts as the centerpiece of blockchain architecture. In distributed networks, consensus protocols not only help maintain data consistency among all stakeholders, but also allow users to work together and stay secure. However, limited efforts have been delivered to analyze and compare existing consensus protocols under various construction scenarios, leading to uncertainties when applying blockchain technology in the construction domain. Therefore, this paper performs a critical review extracting literatures from (1) blockchain-based applications in the construction industry, and (2) existing blockchain consensus protocols. Additionally, a mixed method that integrates qualitative and quantitative analysis is proposed to evaluate the suitability of mainstream consensus protocols for various construction-related applications. Based on the selection criteria and efficiency requirements of consensus protocols generated, a recommendation strategy is also presented for consensus protocol selection under different construction scenarios. This study contributes to the following: (1) it helps construction stakeholders to understand the consensus process in a specific construction application case, and (2) it provides lucid reference guidance in developing a robust blockchain-based system underlying an appropriate consensus protocol. • Reviewed blockchain applications in the construction industry to categorize its implementations. • Identified mainstream consensus protocols and compared their features via four dimensions. • Proposed a qualitative and quantitative analysis method for consensus evaluation. • Generated criteria and requirements for consensus selection under different construction scenarios. • Evaluated consensus suitability and proposed a recommendation strategy for blockchain-based applications. [ABSTRACT FROM AUTHOR]

Data accountability (i.e., data integrity and traceability) concerns existing construction cost management platforms due to the risk of data manipulation in a centralized paradigm. Blockchain is a promising technology that provides immutable and traceable data storage with a decentralized architecture. However, the transparency of blockchain conflicts with the confidentiality nature of cost information. Therefore, this paper presents a novel framework based on blockchain and encryption to preserve both data accountability and confidentiality in construction cost management. The proposed new framework involves the development of a cost data model containing the required confidential cost information to facilitate partially transparent recordings on the blockchain. An access control model based on symmetric and asymmetric encryption as well as proxy re-encryption mechanisms is developed to prevent unauthorized access to sensitive cost data on the blockchain and transfer data access in dynamic construction projects (i.e., construction projects involving new members continuously). Subsequently, encryption-integrated smart contracts are developed for automatic and secure cost activities on the blockchain. The framework is validated with a desirable latency (at the millisecond level), throughput (at the hundred level), and storage cost (at the MB level) in three illustrative cost management scenarios. The results indicate that project members can have accountable and confidential cost data for dispute resolution and cost analysis, respectively, as well as efficient cost data access transfer. • A framework based on blockchain and encryption for construction cost management. • Identification of confidential cost data models for partially transparent blockchain recording. • Proxy re-encryption mechanisms for cost information access transfer on blockchain. • Encryption-integrated smart contracts to automate and secure cost activities on blockchain. • Latency in msec, TPS in hundred and storage cost in MB in 3 illustrative scenarios. [ABSTRACT FROM AUTHOR]

Building Information Modeling (BIM) is widely adopted for design collaboration in the architecture, engineering, and construction (AEC) industry, while its centralized paradigm suffers the risk of data manipulation. To this end, blockchain is an emerging distributive technology that guarantees data authenticity and integrity by providing decentralized, immutable, and traceable data storage. However, directly integrating BIM with blockchain risks leaking sensitive data, since a blockchain is a transparent network insofar as shared information (including sensitive data) can be disclosed to all members without access control. Therefore, this paper proposes a confidentiality-minded framework (CMF) for blockchain-based design collaboration. The major innovations are twofold. First, an access control model is developed in the CMF to prevent unauthorized access to sensitive BIM data in a blockchain ledger. Second, new design strategies are developed in CMF to facilitate design coordination within the access-controlled blockchain network. An illustrative design example validates the feasibility and performance of the proposed CMF, which has acceptable latency and storage cost. The results also show that the sensitive BIM data are effectively kept confidential when project members collaborate within the CMF. • Proposed an access control model to protect sensitive BIM data in the blockchain ledger. • Developed BIM component-based workflows for design coordination in an access-controlled blockchain network. • Developed a BIM Merkle tree (BMT) data model and BMT algorithms for efficient versioning of BIM components. • Validated the feasibility and performance of CMF through an illustrative example. • Results show that the CMF can protect BIM confidentiality in the blockchain-based design collaboration. [ABSTRACT FROM AUTHOR]