The adoption of prefabricated building systems has grown due to the need to reduce duration and cost of construction projects, as well as to improve quality and working conditions. However, the adoption of those systems requires an intense exchange of information to integrate the production of components, logistics operations, and site assembly. This is particularly important in engineer-to-order environments, in which the level of uncertainty tends to be high. This research proposes a model for planning and controlling the delivery and assembly of ETO prefabricated building systems, emphasizing the integration between site installation and logistics operations. This model was devised in an empirical study carried out in a company that delivers and assembles prefabricated concrete structures. The main theoretical contribution is a set of approaches to implement the “pull production” and “reduce variability” principles in this particular context, exploring synergies that exist between Lean Production principles and Building Information Modeling (BIM) functionalities.

Managing industrialised construction requires an accurate synchronisation of design, manufacturing and assembly processes. Considering the high uncertainty and the interdependences between different processes on site, it is important to consider the status of the construction site in the planning and control process. Understanding the demands of site assembly in terms of components is a key step for integrating fabrication and site assembly. One possible approach is to use Building Information Modelling (BIM) for planning the logistics operations of prefabricated building systems.The aim of this paper is to describe an application of BIM 4D modelling for supporting the planning and control process of logistics operations for Engineer-toorder (ETO) concrete prefabricated structures. Design Science Research was the methodological approach adopted in this investigation, which involved an empirical study carried out in partnership with a company that design, produces and assemble prefabrication concrete structures. The main contribution of this investigation is on how to increase the reliability of information exchanges by concentrating product and process information in a BIM model. Also, some guidelines on how to plan loading and unloading operations, and how to use BIM to assess changes in production plans, considering the logistics impacts.

Resumogestão de sistemas pré-fabricados demanda uma intensa troca de informações entre a fábrica e a obra, de forma a sincronizar a fabricação, as operações logísticas e o processo de montagem, principalmente em ambientes engineer-to-order, no qual o nível de incerteza tende a ser alto. A literatura sugere o uso de Building Information Modeling (BIM) para facilitar o compartilhamento de informações e apoiar a tomada de decisões, assim como a aplicação de conceitos e princípios da Produção Enxuta. Particularmente em relação ao processo de montagem, o BIM 4D pode ser utilizado para simular algumas operações, apoiando o planejamento e controle da produção. O presente artigo propõe um conjunto de diretrizes para a utilização do BIM 4D e conceitos e princípios da Produção Enxuta para apoiar a gestão logística do processo de montagem de sistemas pré-fabricados em concreto do tipo engineer-to-order. Foi adotada a abordagem metodológica da Design Science Research, tendo por base um estudo empírico realizado em uma empresa que fornece estruturas pré-fabricadas de concreto. As principais contribuições do trabalho referem-se o uso de BIM 4D para padronizar as operações logísticas e para a gestão de informações relacionadas ao status do sistema. Palavras

Information pulled from 4D simulations may be used to compare construction scenarios as well as to support decision-making in production planning and control. Different projects, software, tools and planning methods result in a diversity of inputs that should be considered while trying to fulfil 4D simulation needs. If those are not properly addressed, it may lead to inconsistencies and lack of suitable information. The existing literature on 4D BIM does not provide much advice on which information should be considered to develop a 4D simulation. The aim of this paper is to propose a set of guidelines to devise BIM models to support production planning and control with emphasis on Lean Construction principles and concepts. Design Science Research was the methodological approach adopted in this investigation, which was based on three empirical studies. The main contributions of this study are concerning with understanding the sources of information for3D modelling and how information should be gathered so that 4D BIM model scan effectively support planning and control decisions. A model based on these guidelines should provide relevant information to support decision making, and consequently contribute to reduce variability, increase data reliability, eliminate nonvalue adding activities and reduce 3D modelling time.

Resumo Os potenciais benefícios do uso de sistemas construtivos pré-fabricados do tipo engineer-to-order (ETO) abrangem desde a redução de custos e duração do empreendimento até melhorias na qualidade do produto. Entretanto, o escopo de sistemas de planejamento e controle da produção neste contexto deve ser diferente de empreendimentos tradicionais, pois existe a necessidade de coordenar diferentes tipos de fluxos (projeto, fabricação, operações logísticas e montagem). Neste contexto, é necessária a estabilização desses fluxos e consequente diminuição do trabalho em progresso, o que é relacionado ao esforço de reduzir o tamanho do lote de produção. O objetivo do presente trabalho é propor um conjunto de diretrizes para a definição dos lotes de montagem para sistemas pré-fabricados de concreto do tipo ETO com apoio de BIM 4D, com base em conceitos e princípios da produção enxuta. Design Science Research foi a abordagem metodológica adotada, tendo como base um estudo empírico em uma obra de ampliação de um aeroporto. As principais contribuições do trabalho são um conjunto de categorias de decisão para a definição dos lotes de montagem, e o desenvolvimento de ferramentas para apoiar a tomada de decisões.

Flow is a key concept in Lean Production and is particularly important in construction. Due to the complexity of projects, in part due to managerial practices adopted, much variability exists in construction resource flows. Production system design can be used to eliminate at least some unwanted variability and then reduce the impact of remaining variability by using buffers in order to improve such flows. Accordingly, planners may add buffers of certain sizes in certain locations into the system, or use more systematic, adaptive, data-driven methods. With this in mind, the authors initiated a systematic literature review (SLR) on buffers in construction. The paper contributes to knowledge by defining the term 'buffer' and providing a characterization of buffer types and methods of deployment. Despite advances in understanding and method development, no one method stands out. The methods as described fall short of being able to both proactively determine buffer sizes and locations in the production system to suitably accommodate anticipated needs, and also reactively adjust them in light of system design changes. The use of SLR as the research methodology has well-known limitations, but the findings were revealing, and follow-on research will cast a wider net for relevant literature.

Construction projects are known to be complex, due to being subject to uncertainty and variability. The use of buffers to protect them from the detrimental impact of variability has been well-researched. A key managerial choice is not whether or not to buffer variability, but rather how to define the necessary combination of buffers. Slack is a concept related to buffers but has been used in the literature to describe a broader range of strategies for coping with complexity. It allows an organisation to adapt to internal pressures for adjustment or to external pressures for change in policy. This paper aims to further develop the concept of slack and to unveil its relationships with other concepts and ideas that are partly overlapping such as buffers, resilience, robustness, flexibility, and redundancy. A concept map was devised in order to articulate the nature of the slack concept. This paper explores in detail this concept map and proposes a conceptual role for slack in the realm of Lean.

No abstract