Abstract BIM-based quantity takeoff is faster, more accurate, and more reliable than traditional quantity takeoff. However, the quality of BIM models is a major issue. Quantity takeoff is inaccurate for compound elements such as walls and floors modeled as single model elements with defined material layers because the size and composition of each layer cannot be freely adjusted. Furthermore, overlapping regions of compound elements with other elements result in excess material quantities. Manual inspection and modification of each compound element are time-consuming, cost-intensive, and error-prone. This study proposes a method to automatically modify compound elements in BIM models by separating each layer into an individual model element and eliminating overlapping regions. Accurate material quantities for compound elements can be obtained from the modified BIM models. A prototype system was developed and the proposed method was validated by two case studies. Compared to manual modification, the proposed method successfully modified compound elements in BIM models in much less time, with accurate material quantities. The modified BIM models are also beneficial in the construction phase, which requires greater detail regarding BIM elements.

中文翻译：

---

自动修改复合元素以实现基于 BIM 的准确数量计算

摘要 基于BIM的工程量计算比传统的工程量计算更快、更准确、更可靠。然而，BIM模型的质量是一个主要问题。对于作为具有定义材料层的单个模型元素建模的墙和地板等复合元素，数量计算是不准确的，因为无法自由调整每一层的大小和组成。此外，复合元素与其他元素的重叠区域会导致材料数量过多。手动检查和修改每个复合元素既费时又费钱，而且容易出错。本研究提出了一种通过将每一层分离为单个模型元素并消除重叠区域来自动修改 BIM 模型中复合元素的方法。复合元素的准确材料数量可以从修改后的 BIM 模型中获得。开发了一个原型系统，并通过两个案例研究验证了所提出的方法。与手动修改相比，所提出的方法在更短的时间内成功地修改了 BIM 模型中的复合元素，并具有准确的材料数量。修改后的 BIM 模型在施工阶段也很有用，这需要关于 BIM 元素的更多细节。