# Analysis of BIM-Based Quantity Take-Off in Simplification of the Length of Processed Rebar
## 3 Methodology & Results
### Selection of Calibration Lengths and Quantity Take-Off
#### 3.2.4. Slabs  
The slab is arranged in both the short-side and the long-side directions (\(X\)- and \(Y\)- axis respectively). In addition, depending on the location of the beam, the deformation increases as the distance from the beam increases. As a result, the beam is divided into the column and middle strip sections to design the rebar arrangement for slabs. Furthermore, additional rebar arrangements for slabs must be performed for relatively vulnerable areas, such as openings. The QTO of slabs requires six types of design drawings, including arrangement drawings for the top and bottom \(X\)-axis, the top and bottom \(Y\)-axis, and the top/bottom reinforcement drawings. Figure 5 below shows an example of the rebar arrangement of slab members and the name of the rebar for each part.  
The lengths of the processed rebar of the slab member were calibrated by allocating them into the unrefined case (10 mm), Case A (100 mm), Case B (300 mm/500 mm/700 mm/1000 mm), and Case C (500 mm/1000 mm). The results of the arrangements of the rebar and QTOs are captured in Tables 7 and 8, as follows. As in the case of the beam, the results of QTO for the buildings of the project were summed. In addition, the differential was calculated for each case for the unrefined case. Based on Case C, Project C (+2.16%) showed the largest increase rates in the amounts of rebar materials, and Project G (\(-\)53.08%) showed the largest decrease in the number of LPRS. The QTO results and differentials for each building of each project are included in Tables A8 and A9 in Appendix A. Table A8 shows the calculated amounts of rebar materials by building for slab members by case, and Table A9 shows the calculated number of LPRS.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Types of Rebar Lengths (Units)**} \\ \cline{3-7}  & **Unrefined** & \multicolumn{2}{c}{**Case A**} & \multicolumn{2}{c}{**Case B**} & \multicolumn{2}{c}{**Case C**} \\ \cline{3-7}  & **Val.** & **Diff.** & **Val.** & **Diff.** & **Val.** & **Diff.** \\ \hline
**Project A** & 1823 & 1750 & \(-\)4.00\% & 1675 & \(-\)8.12\% & 1529 & \(-\)16.13\% \\
**Project B** & 1659 & 1302 & \(-\)21.52\% & 1147 & \(-\)30.86\% & 1043 & \(-\)37.13\% \\
**Project C** & 2431 & 1968 & \(-\)19.05\% & 1822 & \(-\)25.05\% & 1718 & \(-\)29.33\% \\
**Project G** & 4536 & 3662 & \(-\)19.27\% & 3463 & \(-\)23.66\% & 3333 & \(-\)26.52\% \\
**Project H** & 15,184 & 12,304 & \(-\)18.97\% & 10.416 & \(-\)31.40\% & 8922 & \(-\)41.24\% \\ \hline \hline \end{tabular}
\end{table}
Table 6: Numbers of LPRS for Beam Members and Differentials by Cases.  
Figure 5: Example of the rebar arrangement of slab members and the name of the rebar for each part (1F, Building #101 of construction project A).  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Amount of Rebar Material (Ton)**} \\ \cline{3-7}  & **Unrefined** & \multicolumn{2}{c}{**Case A**} & \multicolumn{2}{c}{**Case B**} & \multicolumn{2}{c}{**Case C**} \\ \cline{3-7}  & **Val.** & **Diff.** & **Val.** & **Diff.** & **Val.** & **Diff.** \\ \hline
**Project A** & 212.9 & 214.1 & +0.58\% & 215.9 & +1.44\% & 218.9 & +2.82\% \\
**Project B** & 267.9 & 269.4 & +0.55\% & 271.8 & +1.44\% & 275.2 & +2.72\% \\
**Project C** & 818.8 & 832.5 & +0.57\% & 831.5 & +1.56\% & 843.0 & +2.96\% \\
**Project G** & 551.3 & 554.1 & +0.50\% & 558.8 & +1.35\% & 566.6 & +2.78\% \\
**Project H** & 1584.2 & 1595.9 & +0.73\% & 1622.2 & +2.40\% & 1658.3 & +4.67\% \\ \hline \hline \end{tabular}
\end{table}
Table 5: Amounts of Rebar Materials for Beam Members and Differentials by Cases.