Off-site Manufacture Research Articles

Replacement Pooley Bridge in Cumbria: the UK’s first stainless-steel road bridge

Completed in 2021, the new Pooley Bridge in Cumbria is the UK’s first stainless-steel road bridge. It replaced an iconic 1764 stone bridge that was destroyed in a storm. The enforced 18 km detour meant a replacement was quickly needed, but the World Heritage location demanded a high-quality design too. The solution was an elegant and innovative stainless-steel structure that has become a tourist attraction in its own right. This paper describes the design, offsite manufacture and construction of the multi-award-winning crossing.

Analysis on risk factors related delay in PCPs

PurposeRisk factors related delay hinder the schedule performance of most construction projects in the world. It is a critical challenge to realize the advantages of prefabricated construction projects (PCPs) under the negative effect of schedule delay. This paper aims to propose an exhaustive list of risk factors impeding the progress of PCPs and evaluate the collected risk factors based on the cause–effect relations. The ultimate goal is to improve the understanding of the complex relations among various risk factors related delay in PCPs, and also offer managers a reference on aspect of schedule risk management.Design/methodology/approachThis paper proposes a hybrid method of GT–DEMATEL–ISM, that is combing grounded theory, DEMATEL (decision-making trial and evaluation laboratory) and ISM (Interpretative Structural Modeling), to collect, evaluate and structure risk factors related delay for PCPs. The research procedure of this methodology is divided into three stages systematically involving qualitative and quantitative analysis. In the first stage, GT is utilized to implement qualitative analysis to collect the risk factors leading to schedule delay in PCPs. While, the quantitative analysis is to analyze and evaluate the collected risk factors based on the cause–effect relations in the next two stages evaluation by the DEMATEL focuses on quantifying the priority and intensity of the relations between factors. Additionally, ISM is employed to construct the hierarchical structure and graphically represent the pairwise relations between factors.FindingsThe outcome of qualitative investigation by grounded theory proposes a theoretical framework of risk factors related delay for PCPs. The framework contains three levels of category, namely, core category, main category and initial category and provides a list of risk factors related delay. Following this finding, evaluation results by the DEMATEL classify factors into cause and effect groups and determine 11 critical delay risk factors. Meanwhile, the findings show that risks referring to organizational management issue foremost impact the progress of PCPs. Furthermore, a systemic multilevel hierarchical structure model is visually constructed by ISM to present the pairwise linkages of critical factors. The model provides the risk transmission chains to map the spread path of delay impact in the system.Originality/valueThe contribution of the study involves twofold issues. Methodologically, this research proposes a hybrid method GT–DEMATEL–ISM used to identify and analyze factors for a complex system. It is also applicable to other fields facing similar problems that require collecting, evaluating and structuring certain elements as a whole in a comprehensive perspective. The theoretical contribution is to fill the relevant research gap of the existing body of knowledge. To the best knowledge of the authors, this paper is the first attempt to integrate qualitative and quantitative research for risk analysis related delay and take the insight into the whole process of PCPs covering off-site manufacture and on-site construction. Furthermore, the analysis of findings provided both a micro view focusing on individual risk factor and a managerial view from a systematic level. The findings also contribute the effective information to improve the risk management related schedule delay in PCPs.

Trent Brick Panel: innovative envelope system designed according latest UK national fire and energy performance regulations

In November 2018, following the Grenfell Tower tragedy in London, the Ministry of Housing, Communities & Local Government (MHCLG) introduced an amendment to the Building Regulations 2010, which outlined stricter rules banning the use of combustible materials defined by the new Building Regulation 7(2). This change had a significant impact since early 2019, on the materials and systems that can be used in the construction sector. In 2020, the global pandemic caused by the diffusion of the COVID-19 virus represented a new challenge for the industry, with implications on programme certainty, material procurement, workforce management, moving towards offsite manufacture. The development of the Trent Brick Panel is set against this historical and social context. The envelope prototype is the opportunity for innovation that follows the turn of events. The offsite manufacturing of glass-reinforced concrete panel, mimicking several finishes, is the result of a design investigation carried out with the market-leading actors: developers, main contractors, subcontractors, engineering consultancies, architects, local authorities and warranty providers. The research aims to give an overview of the design principles, sequence and buildability study, assessed weathering performance according to CWCT Sequence B test and fire performance.

Performance of modular hybrid cold-formed/tubular structural system

In recent years, modular construction has been used in low-to medium rise multi-story and even high-rise buildings. Pre-fabrication by off-site manufacture leads to faster and safer construction, improved quality, reduced resources and waste. The research activity summarized in this paper is carried out within the European project INNO3DJOINTS and it aims at developing innovative plug-and-play joints which enable modularity, faster construction and deconstruction. The developed modular construction system is hybrid, whereby tubular columns are combined with cold-formed lightweight steel profiles using plug-and-play connections to provide an efficient structural system. The influence of the type of floor system, the horizontal and vertical load-bearing systems and the type of truss on the structural performance are investigated. The results obtained from numerical analyses allowed optimizing the geometry of the examined hybrid modular system. To highlight its effectiveness and versatility, a case study building was used to compare the proposed hybrid system with other conventional structural solutions.

Workers’ safety behaviors in the off-site manufacturing plant

Purpose Although research on prefabricated construction has gained increasing attention in recent years, limited efforts have been devoted to investigating safety issues in the off-site manufacture, especially workers’ behavioral intentions to work safely. Thus, research is needed to identify the motivational factors determining off-site construction workers’ safety behaviors. The purpose of this paper is to investigate workers’ safety behavior by examining the determinants of behavioral intention in the off-site manufacturing plants in China. Design/methodology/approach Theory of planned behavior (TPB) was modified and used in this study to explain how the elements in the hypothesized model interact. Data were collected using a questionnaire. Structural equation modeling technique with partial least-squares estimation was used to analyze the data collected. Findings The findings of this study indicated that workers’ tendency to engage in safety behavior is positively related to attitude toward the behavior, subjective norm, perceived behavioral control and behavioral habit, among which attitude toward the behavior and behavioral habit have most significant influences on safety behavior. This finding provides a better explanation on the pathways and the impacts of the crucial factors on the safety behaviors for the off-site manufacture. Originality/value The possible innovation of this research lies in its attempt to understand the antecedents of workers’ safety behavior in the off-site construction environment, which may make original contributions to construction safety research and practice. The findings of this study contribute to the body of knowledge in TPB. Corresponding countermeasures are put forward in order to improve workers’ safety behavior in off-site construction.

Modularisation and offsite in engineering construction: an early decision-support tool

Modularisation and offsite manufacture are increasing in the engineering construction sector. Decision-support tools for determining a project’s suitability for offsite modular construction are currently limited or outdated, leading to decisions being based mainly around capital cost, experience or intuition. This paper reports on the development of a robust, empirically based decision-support tool for decision makers and clients. A mixed method methodology was conducted involving engineering construction clients, contractors, consultants and suppliers from all over Europe, after which the tool was developed, piloted and validated with practising engineers. It is the first globally applicable tool enabling informed and auditable decisions on using an offsite modular approach for project delivery.

Performance-based control of variability and tolerance in off-site manufacture and assembly: optimization of penalty on poor production quality

Defects and quality problems in off-site manufacturing of building parts are caused by different variables. Subsequently, rework is required during on-site subassembly aggregation. Rework and tampering with prefabricated parts has implications including suboptimal structural/non-structural performance, delays and increased costs. Currently there is a gap in the off-site construction literature in developing effective interventions to reflect on variability in operations of subassembly manufacturers. On this basis, and in the first step of the current research, point clouds of the as-built status of parts are generated by laser scanners and compared with the as-designed status represented by Building Information models (BIM). Then, optimization modelling is used for development of a balanced penalty and incentive (PI) scheme to minimize variability. For this purpose, total expenditure on variability reduction is offset by revenues generated from penalties on poor quality. This optimization-based research contributes to the off-site construction literature by providing cost-effective solutions to quality problems. Furthermore, models and findings are of practical importance to off-site manufacturers by encouraging precision and discouraging discrepancy.

Engineering modular systems for high-rise buildings: an update

Off-site manufacture of ‘plug and play’ modules is fast gaining ground in the plant and housing sectors. Wei Pan, Ray Su, Yancheng Cai and Ben Young of The University of Hong Kong outline the engineering challenges of modular high-rises and suggest some solutions.

Enhancing high-rise residential construction through design for manufacture and assembly – a UK case study

Buildings forms are often complex and a result of end user needs, local surroundings and aesthetic aspirations. The individuality of buildings has therefore posed challenges with respect to harnessing the desired mass production and standardisation linked with off-site manufacture. However, through design for manufacture and assembly (DfMA), construction can be linked with industrial processes and deliver projects that are safer, cleaner and more efficient. Furthermore, successful DfMA projects minimise disruption within the local environment while delivering not only improved quality, cost and programme certainty, but also a more sustainable form of construction. The Two Fifty One project is a 40-storey mixed-use development in central London, UK, that has successfully embraced the principles of DfMA across all engineering disciplines. As a result, the delivery team has developed effective off-site construction solutions for superstructure, facades, bathrooms and mechanical and electrical services. All have been designed, coordinated and facilitated through advanced digital engineering and building information modelling techniques. Overall, the project has been delivered with reduced programme and cost, while simultaneously improving safety, quality and reliability in a more sustainable way through reduced vehicle movements and greater efficiency in site logistics. This case study describes this exemplary project and the design delivery model.

BIM in off-site manufacturing for buildings

The need to overcome challenges faced by construction industry has been at the core of many government reports. Most of the reports suggest the adoption of innovations including off-site manufacture and emerging Building Information Modelling (BIM) to overcome the challenges facing the industry. Current research has largely focused on the impacts of off-site manufacture and BIM independently applied on traditional construction methods. Due to the factory-based nature of off-site manufacture, the benefits of BIM on off-site manufacture have been widely argued to be far greater than those of traditional construction. However, studies about impacts of BIM on off-site manufacture are scarce with far too many on traditional construction. This study investigates the implications of BIM systems on off-site manufacture and traditional construction methods, with emphasis on the technological potential of BIM for off-site manufacture. The specific objectives of the study are threefold. Firstly, it examines how BIM can support off-site manufacture. Secondly, the paper discusses the benefits of BIM and explains how BIM can overcome barriers hindering the uptake of off-site manufacturing. Thirdly, due to the importance to measure the benefits to support wider adoption, an examination of the published quantitative benefits of BIM on off-site manufacture and traditional construction is undertaken. A critical appraisal of the literature was undertaken to achieve the aim of this study. The main findings are the identification of qualitative and quantitative benefits of: BIM on off-site manufacture, off-site manufacture and BIM on traditional construction. The findings reinforce the argument that BIM adoption on off-site manufacturing projects is a rapid, efficient and one of the best ways to improve on the long standing challenges that have plagued the construction industry for generations.

Insights into Architects’ Future Roles in Off-Site Construction

Today’s construction industry is overflowing with new ideas about its future. Off-Site Manufacture and Construction (OSCM) is at the heart of the modern construction industry. Much has been written about the state and context of OSCM in different countries regarding its perceived benefits and barriers to implementation. Off-site production (OSP) plays an important role in improving fragmented construction processes. Although most OSP research targets the attitudes and practices of OSP adoption, there is limited understanding of the philosophical issues underpinning OSP-related architecture. The roles of the architects’ personal philosophies are neglected and this hampers their implementation of OSCM (which has had a largely technical focus). This paper explores the traditional thinking patterns of architects in China and predicts possible future roles for them. It then conceptualizes an “architectural work” mode and a “building product” mode of design and construction and identifies the shortcomings of architects in an OSCM environment. The arguments made are based on practitioners’ perceptions and the first author’s practical experiences of leading several real-life projects in recent years. The findings reveal the implications and significance of the transformation from an “architectural work” mode to a “building product” mode. We foresee a study approach that focuses on the order and rules for OSCM, resulting in architects’ existing mindsets being changed to thinking patterns and design methodologies better suited to OSCM.

INNOVATIVE HOUSING ADOPTION: MODULAR HOUSING FOR THE AUSTRALIAN GROWING FAMILY

Housing must be flexible to the circumstances growing families face as their needs change during the family lifecycle. The purpose of this paper is to gather a preliminary understanding of growing families' needs and evaluate how modular off-site manufactured construction could effectively answer those needs. Despite the large amount of research that has gone into off-site manufactured buildings, there is little research that has explored its suitability as a flexible housing typology for growing families. The pilot presented in this paper investigates the specific context of Brisbane, Australia; qualitative data have been gathered from growing families in this city and combined with established theory on flexible building to develop a preliminary understanding of how modular off-site manufactured construction could perform in meeting flexibility requirements in comparison to a traditional lightweight timber framed construction. Findings highlight how the ability to modify a dwelling is a fundamental feature for growing families; a number of other advantages in flexibility were found in modular off-site manufacture and recommendations made to improve this construction typology.

A Two-Sided Mold and the Entrepreneurial Spirit of Pilgrimage Souvenir Production in Late Antique Syria–Palestine

This article offers a new interpretation of a two-sided mold reportedly found near Jerusalem. It argues that the mold was used in the off-site manufacture of clay or soft-metallic souvenirs that could be sold to pilgrims at the cult sites themselves or further afield. It provides a reconsideration of the iconography of the mold, arguing that one side features the unique iconography of Aphrodite of Aphaca, whose shrine was reportedly destroyed under Constantine. It further asserts that the mold’s other side depicts the angels at Mamre in a manner reflective of the site’s cultic topography and designed to appeal to the diverse pagans, Jews, and Christians reported to have visited the site in the fourth century. It thus challenges previous interpreters who have seen the mold’s Mamre image as exclusively Christian and argues that its divergent religious imagery reveals the economic motivation of pilgrimage souvenir manufacture. Based on the mold’s depictions of Aphrodite of Aphaca and Mamre, the literary sources describing the sites, and the visual style of the mold, it contends the object should be dated between the early and mid-fourth century.

Adoption of artificial lightweight aggregate in precast manufacture

This study investigates the incorporation of lightweight sintered pulverised fuel ash (SPFA) as a partial/complete replacement for natural sand and aggregates within full-scale precast elements. It focuses on self-compacting concrete (SCC) mixes after short periods of strength development, owing to the lack of published experimental data for these concrete types and their significance in offsite manufacture. Aggregate failure means the use of SPFA reduces concrete capacity, particularly in shear and pull-out, and such reductions may be more prominent at an earlier stage of curing. These were investigated alongside the incorporation of steel fibres that may provide some compensation. The variation in the compressive strength obtained was less significant (3–5%), following 24 h of curing, than at 28 d (15%). A similar trend was observed across the range of densities and in the tensile and flexural strength tests, with a slightly increased workability also observed in the lightweight mixes. Similar testing of steel-fibre-reinforced concrete (SFRC) samples, with a 50 kg/m3 fibre content, challenges the appropriateness of current code design equations. More efficient element design may thus be possible for precast components where such design cases are prevalent. A 63% average increase in pull-out shear capacity also suggests an improved lifting capacity could be justified within precast elements.

Special Issue on Off-Site Construction

Special Issue on Off-Site Construction

Drivers, constraints and the future of offsite manufacture in Australia

PurposeMuch has been written on offsite manufacture (OSM) in construction, particularly regarding the perceived benefits and barriers to implementation. However, very little understanding of the state of OSM in the Australian construction industry exists. A “scoping study” was recently conducted to determine the “state‐of‐the‐art” of OSM in Australia. The purpose of this paper is to report on the overall findings of the study.Design/methodology/approachThe study took a broad qualitative survey‐based approach. This involved three industry workshops, several interviews and seven case studies across four major states of Australia. The study surveyed a range of suppliers across the construction supply‐chain, incorporating the civil, commercial and housing segments of the market.FindingsThe study revealed that skills shortages and lack of adequate OSM knowledge are generally the greatest issues facing OSM in Australia. OSM uptake into the future is dependent on many factors, not least of which is a better understanding of the construction process and its associated costs. Unlike the USA and UK, the Australian construction industry faces unique challenges in how it transforms construction into a modern and efficient industry.Originality/valueThis is the first work undertaken to determine the benefits and barriers to OSM in the Australian construction industry.

Manufactured Housing: The TVA Experience

As a necessary adjunct to dam building, the Tennessee Valley Authority (TVA) provided worker housing for its construction camps. To this end, TV A architects created a series of designs for economical, demountable houses, all of which exploited the potential of off-site manufacture in sectional units. This article explores the TV A’s refinement of the design and manufacturing of demountable houses and the ideals that underlay them.