# Analysis of BIM-Based Quantity Take-Off in Simplification of the Length of Processed Rebar
## 2 Literature Review  
Numerous studies have been conducted in relation to 3D-BIM-based QTO including rebar materials. For instance, [PERSON] et al. [12] demonstrated the efficiency of BIM software-based QTO by comparing the amount of rebar produced through traditional QTO and BIM software-based QTO. [PERSON] et al. [13] suggested a method of performing rebar QTO using a ratio of amounts (rebar material input to concrete). Meanwhile, various studies have also been conducted considering the reduction in the waste of rebar length. [PERSON] et al. [14] conducted a study to establish a system development foundation for QTO more accurately and quickly, considering the joint and settlement, along with work efficiency, according to the processing type by reinforcement member/distribution. [PERSON] et al. [15] analyzed the rebar material amount according to factors such as the member type, size of the main bar, building size and scale, calculation item, and order length using the BuilderHub software. [PERSON] et al. [16] developed an automatic estimation tool called AutoES. When conducting QTO, AutoES helps calculate to find the rebar combination with the least loss of wasted rebar. This tool can be used for both special orders and market orders. [PERSON] et al. [17] proposed a new method, \"BIM-based compound element quantity takeoff improvement\" (BCEQTI), using information from BIM-based clash detection to eliminate excess quantities and add missing quantities. [PERSON] et al. [18] suggested a Column-Generation-based approach that provides the most cost-effective arrangement of rebar based on the customer-specified maximum heterogeneity. [PERSON] et al. [19] optimized the use of available market-length rebars for generating the least possible waste using BIM modeling and mixed-integer linear programming. The materials are rebars used for RC structures. However, these studies considered only the reduction of wasted rebar, not work efficiency or LPRS, and they can only be used for the field processing method. Meanwhile, [PERSON] et al. [20] proposed an optimal procurement and cutting plan for rebar and presented an optimization solution for rebar cost and volume loss. In this study, the Pareto optimization technique was applied to simultaneously reduce overall cost and lower material waste. Although it considers the length of wasted rebar together with labor, it can be used only for field processing methods, too. Furthermore, this study is about the optimization of rebar detailing design and installation planning, and it can be said that the direct relationship with QTO is small. Numerous studies have been conducted related to 3D BIM-based QTO including rebar materials. In addition, it was confirmed that research related to the reduction of wasted of rebars has been actively conducted until recently. In particular, most of this type of research was conducted with the aim of minimizing material costs or securing sustainability. On the other hand, few studies have been conducted considering work efficiency or LPRS along with the reduction of wasted of rebar regarding 3D BIM-based QTO. In the case of minimizing the waste of rebar, work efficiency decreases due to the increase in the number of LPRS, so these various factors should be considered at the same time. In addition, most of the existing studies are related to the field processing method of rebars, and it is difficult to apply them to the factory processing method. Therefore, this study considered the decrease in LPRS with the increase in the amount of rebars due to the simplification of the length of rebars and the applicability for the factory processing method. Previous studies related to QTO and the calculation of rebar loss reviewed in this section are summarized in Table 1 below.