BIM-based formwork and cladding quantity take-off using visual programing

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2021-9-09
Çepni, Yaşar
Material quantity take-off (QTO) is an indispensable work item in construction projects since it is essentially utilized for scheduling and cost calculation. Traditionally, quantities are calculated based on 2D drawings, which require significant time. It is also an error-prone process because of human inclusion. Moreover, during the project execution, the take-off process gets tedious due to design revisions, missing information, accumulated errors, and inevitable mistakes while performing QTO. Hence, the architecture, engineering, and construction (AEC) industry have been paving the way for implementing Building Information Modeling (BIM) for material QTO and other crucial tasks in the building industry, such as visualization, design analysis, and clash detection. However, the reliability of BIM-based QTO is being questioned among construction practitioners. It is because, and according to the literature, the accurate and automated calculation of area-based materials like formwork and architectural claddings using BIM remains problematic. The reason is mainly due to lack of modeling conventions, agreed workflows among project participants, erroneous modeling process, and limitations of BIM software. Previous studies proposed various modeling approaches, methods for querying BIM models for quantities, creating bridges between BIM-based QTO and take-off standards, and especially recent studies suggested using visual programing for more accurate and reliable BIM-based QTO. Therefore, two different methodologies are developed in this thesis to obtain accurate formwork and architectural cladding QTO within the context of visual programing. Then, a case study is implemented using Autodesk Revit and Dynamo to test the proposed methodologies. Meanwhile, the current software capability for BIM-based QTO is investigated while verifying case study results. Accordingly, results indicate that the algorithms developed in Dynamo successfully obtain material quantities more accurately, and it is also capable of automatically creating 3D models with essential information for formwork and architectural elements. The main contributions of this study are the proposed frameworks, visual codes, and showing the limitations and capabilities of one of the most commonly used BIM tools and problems during the execution of the case study. This research can also be further improved for 4D scheduling, clash detection, and most importantly, new studies in IFC (Industry Foundation Classes) format can be performed for enabling QTO with neutral and open format approaches.

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Citation Formats
Y. Çepni, “BIM-based formwork and cladding quantity take-off using visual programing,” M.S. - Master of Science, Middle East Technical University, 2021.