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This study evaluates the implementation of circular economy (CE) design strategies in mass timber construction to identify knowledge gaps and define crucial future research areas for promoting CE design adoption in this field.

A two-stage systematic literature review (SLR) was conducted to, first, identify CE design strategies applicable to the construction industry and then investigate the current state of CE design research in mass timber construction. Scopus and Web of Science databases were searched for relevant literature. In total, 52 peer-reviewed journal articles published between 2016 and 2023 were shortlisted. Descriptive and thematic analyses were then employed to analyse and synthesise the relevant literature.

Seven CE design strategies were identified in the first stage of the SLR. The second stage of the SLR revealed limited research on CE design strategies in mass timber construction. Several research problems were identified, including a lack of suitable connectors for the deconstruction phase, durability concerns, insufficient knowledge of CE design methods, lack of knowledge and education about mass timber construction, missing actors within the value chain, higher cost, an underdeveloped market and inadequate regulatory requirements. These findings highlighted the future research directions to foster CE design adoption in mass timber construction.

The study systematically identifies existing knowledge on the application of CE design strategies in mass timber construction. Moreover, it presents a conceptual framework that links current research problems to future research directions across technical, social, economic and regulatory categories, thereby advancing CE practice in mass timber construction.

The purpose of this paper is to improve the understanding of the impact of mass timber construction methods on construction performance through the successful delivery of the first-of-a-kind tall wood building, Brock Commons Tallwood House (Tallwood House). This paper is one of a set of papers examining the project; companion papers describe innovations used during the mass timber design and construction processes.

A mixed-method, longitudinal case study approach was used in this research project to investigate and document the Tallwood House project. Quantitative data were collected to perform the following analysis: hook time, the variability of productivity and schedule reliability. Members of the research team observed construction progress, meetings and decision-making, conducted periodic interviews and reviewed project artifacts.

The research presented in this paper is the culmination of a longitudinal study aimed at studying the innovation process on a project where radical innovations of structural systems were developed. Prefabrication, combined with the use of a virtual design and construction (VDC) model for planning and fabrication and early collaboration with trades, construction managers and consultants, increased the labor productivity of the on-site erection of the mass timber structural components and envelope panels and expedited the construction schedule.

This paper details an in-depth investigation into the construction productivity for a unique building project and lessons learned. The case study chosen is the construction of Tallwood House at the University of British Columbia. Tallwood House was the tallest mass-timber hybrid building in the world at the time of its construction.

The purpose of this paper is to present the construction process innovations that enabled the successful delivery of the hybrid mass timber high-rise building in Canada, the Brock Commons Tallwood House at the University of British Columbia. It is one of a set of papers examining the project, including companion papers that describe innovations in the mass timber design process and the impact of these innovations on construction performance. The focus of this paper is on innovation in the construction phase and its relationship to innovations implemented in previous project phases.

A mixed-method, longitudinal case study approach was used in this research project to investigate and document the Tallwood House project over a three-year period. Both quantitative and qualitative data collection and analysis techniques were used. Members of the research team observed prefabrication and construction, conducted periodic interviews and reviewed project artefacts.

The research identified three innovation “clusters,” including the use of innovative tools, techniques and strategies in the design and construction processes and the role they played in delivering the project. The “clusters” were further characterized according to the type of “connectivity” they afforded, either facilitation, operationalization or materialization. These two perspectives support a compounding view on innovation and help to understand how it can flow throughout a project’s life cycle and across its supply chain. Three process-based innovations were initiated during the design phase, integrated design process, building information modeling and virtual design and construction and flowed through to the construction phase. These were seen to enable the creation of connections that were crucial to the overall success of the project. These innovations were operationalized and enacted through the construction phase as design for manufacturing and assembly and prefabrication, staged construction and just-in-time delivery, integration of safety and risk management and a rigorous quality control and quality assurance process. Finally, a full-scale mock-up was produced for practice and constructability assessment, materializing the radical product innovation that was the mass timber structure. These strategies are used together for a synergistic and integrated approach to increase productivity, expedite the construction schedule and develop an innovative building product.

This paper details an in-depth investigation into the diffusion dynamics of multiple systemic innovations for the construction process of a unique building project, the tools and techniques used by the construction manager and team, and the challenges, solutions and lessons learned.

The purpose of this paper is to study the design process innovations that enabled the successful delivery of a hybrid, mass-timber high-rise building in Canada, the Brock Commons Tallwood House at the University of British Columbia. It is one of a set of papers examining the project, including companion papers that describe innovations used during the mass timber construction process and the impact of these innovations on construction performance.

A mixed-method, longitudinal case study approach was used in this research project to investigate and document the Tallwood House project over a three-year period. Both quantitative and qualitative data collection and analysis techniques were used. Graduate student researchers were embedded within the project team to observe meetings and decision-making and to conduct periodic interviews.

The research highlights a case of a balanced triple-helix system that provided a context for the successful “clustering” of product and process innovation, which were developed and implemented to flow throughout the project’s lifecycle and across its supply chain to provide benefits at each stage. Four significant process-based innovations were implemented at the design phase of the building project to support radical product innovation: an integrated design process, virtual design and construction, designing for manufacturing and assembling and a rigorous quality control and quality assurance process. The product innovations developed through these process innovations were the structural system and the prefabricated envelope system. The context of innovation was seen to allow this “clustering,” which is believed to be a key condition of success and enabled the efficient and successful delivery of the project. Generally, the approach was successful; however, some factors including the number of stakeholders and good-faith collaboration may limit the replicability of these strategies.

This paper presents an in-depth investigation into the instantiation of an innovation system, identified as a balanced triple-helix system, which enabled and facilitated the design and decision-making process for a radical product innovation. Moreover, this paper describes the deployment of a “cluster” of process innovations that flowed throughout the project’s lifecycle and across the project supply chain. This was seen as a key factor in ensuring the successful delivery of the project.

Traditional construction materials and methodologies are often perceived to be unproductive, labour-intensive and detrimental to the environment. Mass-engineered timber (MET) is a new structural material that is capable of overcoming numerous issues that otherwise affect the built environment. This study was formulated to assess the current attitude and perception of young Singaporeans towards the concept of Engineered Timber Residential Buildings (ETRBs).

The study employs the mixed-method approach. Questionnaires were used as the primary mode of data gathering. These were disseminated to Singaporeans between the age of 18 and 35 years. A total of 179 valid responses were gathered. Semi-structured interviews were subsequently conducted with six individuals with different demographics in order to gain further insightful opinions and to allow cross validation of responses.

Statistical analysis revealed that 80% of respondents were willing to accept ETRBs, but a lack of awareness and knowledge of MET and the presence of misconceptions, such as an association with deforestation, may present concerns. The study also revealed that individual acceptance of ETRBs is not affected by demographics.

The production of MET involves lower overall carbon emissions than that of conventional materials, and this also allows adoption of the Design for Manufacturing and Assembly (DfMA) concept and offers the benefit of carbon sequestration. Residential buildings are the second most common building type in Singapore; significant benefits can be gained if MET is used as the primary material for residential buildings. In general, young stakeholders in Singapore welcome the concept of ETRBs, despite possessing uncertainties about ETRBs—understandable given that the material lacks a track record of usage. Public authorities are thus advised to explore the feasibility of materialising the concept of ETRBs as an option for public housing.

This study aims to develop a production-oriented approach for optimal mass-customisation of floor panel layouts in cross-laminated timber (CLT) buildings. The study enables meeting building clients’ unique floor plan requirements at an optimal cost and simultaneously enhances manufacturers’ profit by minimising material and manufacturing process waste.

The present research uses a hybrid approach consisting of field data collection, mathematical modelling, development of a Genetic Algorithm (GA) and scenario analysis. Field data includes engineered timber production information, design data and building code requirements. The study adopts the Flexible Demand Assignment (FDA) technique to formulate a mathematical model for optimising the design of mass timber buildings and employs GA to identify optimal production solutions. Scenario analysis is performed to validate model outputs.

The proposed model successfully determines the load-bearing wall placement and building spans and specifications of floor panels that result in optimal production efficiency and the desired architectural layout. The results indicate that buildings made of a single category of thickness of panels but customised in various lengths to suit building layout are the most profitable scenario for CLT manufacturers and are a cost-effective option for clients.

The originality of the present study lies in its mathematical and model-driven approach towards implementing mass customisation in multi-storey buildings. The proposed model has been developed and validated based on a comprehensive set of real-world data and constraints.

Thermomechanical behavior of intermediate-size beam-to-wall assemblies including Glulam-beams connected to cross-laminated timber (CLT) walls with T-shape steel doweled connections was investigated at ambient temperature (AT) and after and during non-standard fire exposure.

Three AT tests were conducted to evaluate the load-carrying capacity and failure modes of the assembly at room temperature. Two post-fire performance (PFP) tests were performed to study the impact of 30-min (PFP30) and 60-min (PFP60) partial exposure to a non-standard fire on the residual strength of the assemblies. The assemblies were exposed to fire in a custom-designed frame, then cooled and loaded to failure. A fire performance (FP) test was conducted to study the fire resistance (FR) during non-standard fire exposure by simultaneously applying fire and a mechanical load equal to 65% of the AT load carrying capacity.

At AT, embedment failure of the dowels followed by splitting failure at the Glulam-beam and tensile failure of the epoxy between the layers of CLT-walls were the dominant failure modes. In both PFP tests, the plastic bending of the dowels was the only observed failure mode. The residual strength of the assembly was reduced 14% after 30 min and 37% after 60 min of fire exposure. During the FP test, embedment failure of timber in contact with the dowels was the only major failure mode, with the maximum rate of displacement at 51 min into the fire exposure.

This is the first time that the thermomechanical performance of such an assembly with a full-contact connection is presented.

Globally, prefabrication in housebuilding has evolved as an innovative approach to attain sustainability and affordability. However, the SC, including non-producers and producers, of prefabricated housebuilding projects is still not perceptually aligned, hindering innovation diffusion. This paper investigates the contemporary industry perspective on PHB for conceptualisation, market share and growth, innovation diffusion and the producer's role in the context of New Zealand.

An exploratory qualitative research design was chosen to learn the perceptual stance of the industry. A semi-structured survey was conducted, followed by interviews with selected supply chain participants, who were producers and non-producers and had relevant experience in the PHB industry.

This study reports the common terminologies used by supply chain members, with justification and explanation. Further, the perceived market share and growth of the PHB industry are obtained and compared with subsequent studies to determine the capability and capacity. The perception of the diffusion of PHB by type is reported to portray the overall trend of the industry. In the last, the role of producers as the suppliers of PHB projects is investigated to establish the stakeholder positional criticality.

This study can help researchers and practitioners gain insight into the PHB industry from a multi-dimensional perspective. This study is a potential first step to formalise the policy, programme, strategies and action plan for the uptake of the PHB in the New Zealand.

PHB diffusion in the supply chain perspective, considering multi-dimensional aspects, has not been considered in previous studies as government agencies produce most of the literature. This academic research establishes the theoretical linkage towards PHB diffusion and reports the current status.

Cross-laminated timber (CLT) is an innovative construction material that provides a balanced mix of structural stiffness, fabrication flexibility and sustainability. CLT development and innovation diffusion require close collaborations between its supply chain architectural, engineering, construction and manufacturing (AECM) stakeholders. As such, the purpose of this study is to provide a preliminary understanding of the knowledge diffusion and innovation process of CLT construction.

The study implemented a longitudinal social network analysis of the AECM companies involved in 100 CLT projects in the UK. The project data were acquired from an industry publication and decoded in the form of a multimode project-company network, which was projected into a single-mode company collaborative network. This complete network was filtered into a four-phase network to allow the longitudinal analysis of the CLT collaborations over time. A set of network and node social network analysis metrics was used to characterize the topology patters of the network and the centrality of the companies.

The study highlighted the scale-free structure of the CLT collaborative network that depends on the influential hubs of timber manufacturers, engineers and contractors to accelerate the innovation diffusion. However, such CLT supply collaborative network structure is more vulnerable to disruptions due to its dependence on these few prominent hubs. Also, the industry collaborative network’s decreased modularity confirms the maturity of the CLT technology and the formation of cohesive clusters of innovation partners. The macro analysis approach of the study highlighted the critical role of supply chain upstream stakeholders due to their higher centralities in the collaborative network. Stronger collaborations were found between the supply chain upstream stakeholders (timber manufacturers) and downstream stakeholders (architects and main contractors).

The study contributes to the field of industrialized and CLT construction by characterizing the collaborative networks between CLT supply chain stakeholders that are critical to propose governmental policies and industry initiatives to advance this sustainable construction material.

This study examined data from 13 international tall residential timber building case studies to increase our understanding of the emerging global trends.

Data were collected through literature surveys and case studies to examine the architectural, structural and constructional points of view to contribute to knowledge about the increasing high-rise timber constructions globally.

The main findings of this study indicated that: (1) central cores were the most preferred type 10 of core arrangements; (2) frequent use of prismatic forms with rectilinear plans and regular extrusions were identified; (3) the floor-to-floor heights range between 2.81 and 3.30 m with an average of 3 m; (4) the dominance of massive timber use over hybrid construction was observed; (5) the most used structural system was the shear wall system; (6) generally, fire resistance in primary and secondary structural elements exceeded the minimum values specified in the building codes; (7) the reference sound insulation values used for airborne and impact sounds had an average of 50 and 56 dB, respectively.

There is no study in the literature that comprehensively examines the main architectural and structural design considerations of contemporary tall residential timber buildings.