Research On Multi-Component Overlap Deduction Of Quantity Take-Off Based On IFC

With the rapid development of China’s construction industry,the scale of construction projects continues to grow.Among them,the field of engineering costs is faced with a severe technical bottleneck: the lack of effective information sharing and collaborative methods among various disciplines,the heavy workload in the downstream stage,and the relationship between components and project cost information can’t be expressed visually.Accurate quantity take-off is the basis of cost control during the life cycle of a building.However,the traditional quantity takeoff method is of low degree of automation,and complicated with large error,which seriously affects the efficiency of cost management.As a new technology in the field of building informatization,BIM(Building Information Modeling)technology is promising to trigger changes in the cost industry,and IFC(Industry Foundation Classes)is widely recognized as the best open BIM standard for data exchange that provides a reliable foundation for quantity take-off among different disciplines.This study summarizes the characteristics,advantages and disadvantages of the existing quantity take-off methods,and describes the requirements of concrete components’ quantity take-off based on IFC standard.Based on this,the information related to the quantity take-off in the IFC data model is divided and analyzed.The project coding is added to the component by using the extensible mechanism of the IFC standard,and a "two-level collision detection algorithm" is proposed by parsing the quantity-related information in the IFC data model.The algorithm uses Boolean operation of the three-dimensional model to conduct accurate deduction calculations on multi-overlapping concrete components according to the inventory rule,solving the inconsistency problem of engineering quantity calculation when using different software or different modeling paths are used in the same model.Thus,the accuracy of the results is improved.The algorithm is tested by the self-developed NMBIM platform.The case results not only verify the feasibility of automatic calculation of multi-component engineering quantity based on IFC standard,but also indicate that the promotion and development of IFC can provide a new strategy for three-dimensional calculations in line with Chinese norms.