Implementation of Level of Development for BIM Collaboration in Timber Building Subsystems Design: A Case Study of I-Joist Construction Elements

Abstract: Due to time, cost, and environmental challenges, wood has become a more common building material even for more complex buildings. Implementing the concept of Level of Development (LOD) on timber structures could provide a tool for BIM collaboration that may save cost and time, and in the early stages mediate wood as an available building material. Studies explain that LOD enables a high level of content and clarity as well as improved control of the design process. As the concept of LOD heavily focuses on general BIM visualisation, existing research at the time of the study lacks descriptions of how to implement LOD for specific projects. The study aims to develop a framework that could provide the industry with a possible implementation concept that could be further developed on other building systems. The goal of the study is to present a framework of a possible LOD implementation on a timber building system with a detailed description focusing on the structural engineer’s role during the design process. From that the questions of how to apply LOD on different project types as well as what data characteristics vary between these project types will be answered. Stated in previous studies, Integrated Project Delivery (IPD)A  is required for a successful design process is gained by utilising Integrated Project Delivery (IPD) and is especiallyalso essential when working with LOD. LOD is defined as five stages: starting with 100, then 200, 300, 350, 400, and finally 500. For each level of a building system, element, or assembly, the vagueness of information decreases and is therefore visualised differently in a BIM model. The study is based on a qualitative analysis of current data and related work about the design process, LOD, and timber buildings. The framework is mainly built upon five theories, the IPD process, the MacLeamy curve, BIM use purposes, data vagueness determination, and data requirement for timber projects. An interview study was conducted where projects using Masonite Beam’s standardised I-joist system were studied and implemented usingg the framework. The resulting framework presents the percentage information vagueness of how mature the information for a given objects is for different data properties and of each LOD level. The analysis leads to the conclusion that if fulfilling three criteria, 1: Following the IPD process, 2: An effort process similar to MacLeamy, and 3: Utilising BIM, the timber system can be implemented on the framework. However, the closer the project meets the criteria the closer the vagueness values will relate to the framework. The project that utilises a highly standardised building system with predefined data presents even lower vagueness values than the framework. Due to varying scales of project complexities, the data properties that showed the most diverse results between the projects were material information, geometric shape, and element dimensions. The findings from the study could be of further use in another research whose authors defined detailed graphical LOD visualisation in a BIM collaborative environment. The concept is strongly dependent on defined vagueness values that the authors of the research did not focus on how to define, which this framework does. Finding theories that support the assumptions made during the analysis development of the framework is continuing work that could strengthen the framework and its reliability.