# Mechanical Performance of Built-Up Columns
## 4 Numerical Analysis
### Effect of Number of Connector  
To investigate the effect of the number of connectors on the performance of the built-up column, the numerical models with column length ranged from 600-3000 mm were established and each column length had a variable number of connectors, varying from 0-7. An increase in the number of connectors means a decrease in the spacing between connectors. The remaining dimension of these models were consistent with that of the specimen S1, and the details were listed in Table 4. The load-axial shortening curves of models with different number of connectors were compared, as shown in Figure 14. Note that, the number of connectors described here refers to the number of connectors in only one side of the built-up column. From Figure 14, it can be observed that with the increase of the number of connectors, the peak of the curves increases and the ductility of the columns also improves, which shows that increasing the number of connectors can improve the mechanical performance of the built-up column. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**No. ** & **Specimen** & **L (mm)** & **N** & **S (mm)** & \begin{tabular}{c} **P-FEA** \\ **(kN)** \\ \end{tabular}  & \begin{tabular}{c} **STW** \\ **Ratio** \\ \end{tabular}  & \ \begin{tabular}{c} **Pu-AISI** \\ **(kN)** \\ \end{tabular}  & \begin{tabular}{c} **P-FEA/Pu-AISI** \\ **P-FEA/Pu-AISI** \\ \end{tabular}  \\ \hline
1 & L3000S400-7 & 3000 & 7 & 400 & 202.0 & 773 & 303.3 & 0.67 \\ \hline
2 & L3000S500-5 & 3000 & 5 & 500 & 190.3 & 765 & 295.5 & 0.64 \\ \hline
3 & L3000S700-5 (end) & 3000 & 5 & 700 & 183.9 & 739 & 275.8 & 0.67 \\ \hline
4 & L3000S600-4 & 3000 & 4 & 600 & 179.1 & 738 & 286.3 & 0.63 \\ \hline  & L3000S700-3 & & & & 161.0 & 682 & 275.8 & 0.58 \\  & L3000-S700-W200 & & & & (148.6) & (629) & (275.8) & (0.54) \\
5 & L3000-S700-W110 & 3000 & 3 & 700 & (152.5) & (667) & (263.7) & (0.58) \\  & L3000-S700-W200-Strip & & & & (132.9) & (543) & (275.8) & (0.48) \\  & L3000-S700-W200-X & & & & (132.5) & (546) & (275.8) & (0.48) \\ \hline
6 & L3000S1000-2 & 3000 & 2 & 1000 & 152.9 & 665 & 238.2 & 0.64 \\ \hline
7 & L3000S1500-1 & 3000 & 1 & 1500 & 139.5 & 623 & 166.3 & 0.84 \\ \hline
8 & L3000S3000-0 & 3000 & 0 & 3000 & 131.1 & 603 & 45.2 & 2.90 \\ \hline
9 & L2400S400-5 & 2400 & 5 & 400 & 256.0 & 1248 & 303.7 & 0.84 \\ \hline
10 & L2400S500-4 & 2400 & 4 & 500 & 242.4 & 1218 & 295.9 & 0.82 \\ \hline
11 & L2400S600-3 & 2400 & 3 & 600 &Figure 14: Effect of number of connectors: (**a**) column length is 600 mm; (**b**) column length is 1200 mm; (**c**) column length is 1800 mm; (**d**) column length is 2400 mm; (**e**) column length is 3000 mm. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**No.** & **Specimen** & **L (mm)** & **N** & **S (mm)** & \begin{tabular}{c} **P-FEA** \\ **(kN)** \\ \end{tabular} & \begin{tabular}{c} **STW** \\ **Ratio** \\ \end{tabular} & \
\begin{tabular}{c} **Pu-AISI** \\ **(kN)** \\ \end{tabular} &
\begin{tabular}{c} **P-FEA/Pu-AISI** \\ **P-FEA/Pu-AISI** \\ \end{tabular} \\ \hline
18 & L18005900-1 & 1800 & 1 & 900 & 262.9 & 1922 & 252.2 & 1.04 \\ \hline
19 & L180051800-0 & 1800 & 0 & 1800 & 269.6 & 2065 & 125.5 & 2.15 \\ \hline
20 & L12005300-3 & 1200 & 3 & 300 & 335.7 & 3176 & 310.4 & 1.08 \\ \hline
21 & L12005400-2 & 1200 & 2 & 400 & 339.7 & 3415 & 304.3 & 1.12 \\ \hline
22 & L12005600-1 & 1200 & 1 & 600 & 326.2 & 3498 & 287.3 & 1.14 \\ \hline
23 & L120051200-0 & 1200 & 0 & 1200 & 322.5 & 3705 & 210.6 & 1.53 \\ \hline
24 & L6005300-1 & 600 & 1 & 300 & 336.6 & 6768 & 310.6 & 1.08 \\ \hline
25 & L6005600-0 & 600 & 0 & 600 & 340.9 & 7832 & 287.4 & 1.19 \\ \hline  & & & & & & & & **Mean** & 1.11 \\ \hline  & & & & & & & & & **COV** & 0.56 \\ \hline \hline \end{tabular} Note: LSYS-N: LX denotes the length of built-up column is X mm; SY denotes spacing between connectors is Y mm; N denotes the number of connectors is N. S denotes the spacing between connectors. The data in brackets denote the results of four specimens obtained from tests.  
\end{table}