• Journal of KIBIM
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• v.4 no.4
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• pp.13-23
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• 2014

After being introduced, Building Information Modeling (BIM) has been actively applied to the cost estimation of construction projects, and various studies on BIM based quantity take-off have been carried out. In practice, however, these calculations take considerable time, because BIM based quantity take-off is further conducted along with 2D-based quantity take-off. Studies on the quantity take-off using BIM spatial objects have been carried out on early stages of projects, but how this method differs from the existing quantity take-off method and how accurate it is in comparison have rarely been verified. Therefore, by comparing 2D based quantities with quantities through BIM spatial objects, this study analyzed the accuracy of quantity take-off using BIM spatial objects. To this end, the properties of BIM spatial objects and quantity calculable spatial types were analyzed, and existing 2D-based quantities and quantities extracted from BIM spatial objects were compared through a case study. As a result, the quantity of spatial objects found to be more by about 7.13% in 0.05% and therefore, this difference should be considered during quantity take-off using BIM spatial objects. Through the results of this study, we can improve the accuracy of quantity take-off using BIM spatial objects in the early stage of a construction project.

• Journal of KIBIM
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• v.8 no.1
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• pp.56-62
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• 2018

There exists no precedented case of quantity take-off, using parametric modeling, from BIM-based irregular structures. Civil 3D provides earthwork quantity take-off based on surface modeling. Generally, designers should enter data into the specification additionally after extracting quantity estimation from earthwork modeling design. The objective of this report is to suggest the method from quantity take-off to specification of BIM-based earthwork quantities. We intend to investigate earthwork take-off method by Civil3D and explain why parametric information extraction is required for quantity estimation and specification and how information of earthwork quantity based on solid and surface modeling is connected to open quantity take-off module. It is highly expected that this suggestion would be the practical methodology of earthwork quantity take-off and specification in the field of civil engineering.

• Journal of KIBIM
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• v.3 no.2
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• pp.1-9
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• 2013

Currently, various studies and applications related BIM based quantity take-off have been attempted, because of the accuracy of cost estimating and reliability by using the BIM model information in automatical calculation. Finishing works that have a large number of various types and materials need the higher accuracy and reliability on the BIM-based quantity take-off. Therefore, this study compared and analyzed 2D and 3D based quantity through Test-bed and determine the cause of the quantity difference. This verified the accuracy and efficiency in the BIM-based quantity take-off for finishing works. Also this study has been proposed opinions for calculating the exact BIM-based quantity take-off.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.263-267
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• 2015

Stakeholders of a construction project expect cost savings through fast and accurate cost analysis by performing BIM-based quantity take-off (BQT). However, authors have observed that there can be discrepancies in the results of BQT depending on the level of development (LOD) and modeling methods. In addition, since quantity take-off methods are different depending on the construction work items, the combination of LOD, modeling methods of BIM, features of construction work items can cause serious overestimate or underestimate in BQT results. It is necessary to identify what kind of problems can happen and how those problems can be avoided in various construction work items, since the discrepancy of quantity take-off results has great impact on not only cost analysis but also the determination of contract amount and it can cause claims, poor construction quality, cost overruns, and many others later in the construction project. Therefore, this paper focuses the identification of issues and problems of BQT at each construction work item level based on two categorizations of structural works and interior works.

• Korean Journal of Computational Design and Engineering
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• v.20 no.2
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• pp.182-192
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• 2015

In recent years, numerous studies have attempted to extract quantity data by using Building Information Modeling (BIM). In terms of open-BIM based quantity take-off at the early design stage, only few studies were conducted in the field of cost engineering. A lack of compatibility of open BIM for information exchange is postulated as the cause. The Industry Foundation Classes (IFC) extension model has been developed to accommodate the interoperability with quantity take-off software. Improvement of open BIM for quantity take-off needs exchange requirements and model guidelines. For this purpose, the quantity data of IFC models were analyzed using BIM analysis tools. This paper also provides a proposal of requirements on open BIM based quantity take-off at the early design stage. Further this study have been develop the interface system for open BIM based quantity take-off requirements with the results on this study.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.92-93
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• 2019

Estimates based on BIM makes it possible to perform from quantity take-off to construction cost estimates by using model, which is made in the phase of design and construction. As the BIM models are made up of the units of element, there an advantage of the automative quantity take-off, if the correction or change of element occurs. Work items, not included in the elements of the BIM model, are excepted from bill of quantity. Level of detail(LoD) of the BIM model can be improved for detailed estimates, but an excessive modeling for estimates is inefficient. This study presents the measure for selection and quantity take-off of work items, those are not expressed in the BIM model. The proposed method avoids the creation of excessive BIM Models and enables quantity take-off in conjunction with the element.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.7-11
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• 2011

Quantity take-off (QT) is one of the most important tasks for determining the total cost of a construction project, and it requires accuracy and reliability for the result. Accuracy and reliability in BIM-based QT are also required to assure the completeness of the result. However, there has been no basis to measure the completeness of the BIM-based QT result. As BIM is increasingly being adopted in the construction industry with a wide variety of purposes, it becomes more important to have a method to improve the completeness of BIM-based QT and criteria to measure it. This research focuses on the hypothesis that the completeness of BIM-based QT relies on the accuracy and reliability of BIM and the BIM-based QT process. As a basic research to determine the completeness of BIM-based QT, this research analyzes and derives factors that affect the completeness of BIM-based QT.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.1
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• pp.35-44
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• 2020

In the construction industry, there is a growing demand for the accurate calculation of the quantity take-off and construction budget at the design stage, and it is likewise important to grasp changes in the construction budget and quantity take-off if design alterations are made. In addition, lawsuits related to the quantity take-off and cost of construction are frequent; therefore, the calculation of these factors using building information modeling (BIM) has emerged as an alternative. However, existing 2D-based methods are still used more frequently than BIM-based methods for quantity take-offs and construction budgets. This is because of the lack of BIM experience of estimation workers and the absence of a national standard. However, from a designer's point of view, it is necessary to understand the quantity take-off and construction cost based on BIM and accurately create the design according to the budget. In this study, the quantity take-offs of concrete, rebar, and reinforced concrete structures (apartments) in Seoul and Yeongjong were compared with the quantity take-offs based on 2D and BIM methods. From the viewpoint of the designer, we aim to increase the accuracy of BIM-based quantity take-offs.

• Journal of the Korea Society of Computer and Information
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• v.24 no.2
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• pp.127-137
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• 2019

In this study, we have developed a calculation system for BIM-based quantities, 4D process, and 5D construction costs, by integrating object shape attributes and the standard classification system which consist of Cost Breakdown System(CBS), Object Breakdown System(OBS) and Work Breakdown System(WBS) in order to use for the 4 dimensional process control of roads and rivers. First, a new BIM library database connected with the BIM library shape objects was built according to the CBS/OBS/WBS standard classification system of the civil engineering field, and a integrated database system of BIM-based quantities, process(4D), and construction costs(5D) for roads and rivers was constructed. Nextly, the process classification system and the cost classification system were automatically disassembled to the BIM objects consisting of the Revit-family style elements. Finally, we added functions for automatically generating four dimensional activities and generating a automatic cost statement according to the combination of WBS and CBS classification system The ultimate goal of this study was to extend the integrated quantities, process(4D), and construction costs(5D) system for new roads and rivers, enabling the integrated use of process(4D) and construction costs(5D) in the design and construction stage, based on the tasks described above.

• Journal of KIBIM
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• v.7 no.3
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• pp.11-20
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• 2017

BIM technology, which is widely used in the construction industry, has been introduced in various fields for the purpose of saving construction cost and reducing construction schedule. However, in the case of BIM-based cost estimate, there are various trials and errors in applying BIM technology which can be applied for calculating quantity and cost estimate. BIM-based cost estimate can improve the quantity accuracy and allow to easy modifications that were not expected in 2D-based construction process. However, for this purpose, it is necessary to take into consideration that interoperability between BIM data and cost information should be planed in advance. Besides, the definition of a BIM data specification is also required for the seamless data exchange and integrity in each phase of the construction process. Therefore, in this study, we propose a BIM - based cost estimation method and technology in each type of work applicable to the current domestic construction industry.