# The Resistance of Welded Joints of GAlvanized RHS Trusses with Different Vent Hole Geometries
## 3 Validation of Finite Element Modeling
Figures 6 and 7 also show a good agreement between the model and the test for the initial joint stiffness (both curves match very well in this zone). These figures present displacements at two points of the tested joint. No data were available from the tests with respect to deformations at other points for the purpose of comparison with those from the simulation. With respect to the failure mode, as mentioned above, the general configuration of the joints and the combination of braces and chords for the parametric study were selected to predominantly present \"brace failure\". To faithfully reproduce the test, the model created \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Test** & **Gap** & **Joint** & \(f_{y}\) & \(f_{u}\) & **Tangent Modulus** \\
**No** & **(g/\(b_{0}\))** & **Members** & **[N/mm\({}^{2}\)]** & **[N/mm\({}^{2}\)]** & **[N/mm\({}^{2}\)]** \\ \hline \multirow{3}{*}{1} & \multirow{3}{*}{0.10} & Chord: \(258\times 258\times 8.4\) & 289 & 409 & 1110 \\  & & Comp. Brace: \(99.4\times 99\times 6.0\) & 337 & 402 & 802 \\  & & Tension Brace: \(103\times 99\times 5.2\) & 317 & 405 & 932 \\ \hline \multirow{3}{*}{2} & \multirow{3}{*}{0.43} & Chord: \(100\times 100\times 3.8\) & 261 & 363 & 963 \\  & & Braces: \(40\times 40\times 4.0\) & 279 & 383 & 996 \\ \hline \multirow{3}{*}{3} & \multirow{3}{*}{0.15} & Chord: \(100\times 100\times 4.1\) & 462 & 512 & 1291 \\  & & Braces: \(60\times 60\times 4.2\) & 443 & 587 & 1813 \\ \hline \multirow{3}{*}{4} & \multirow{3}{*}{0.15} & Chord: \(99.8\times 99.8\times 4.3\) & 333 & 373 & 907 \\  & & Braces: \(59.7\times 59.7\times 4.4\) & 376 & 411 & 958 \\ \hline \multirow{3}{*}{5} & \multirow{3}{*}{0.10} & Chord: \(102\times 102\times 3.9\) & 363 & 520 & 1440 \\  & & Braces: \(64\times 64\times 3.3\) & 369 & 511 & 1350 \\ \hline \multirow{3}{*}{6} & \multirow{3}{*}{0.10} & Chord: \(102\times 102\times 4.2\) & 321 & 501 & 1550 \\  & & Braces: \(64\times 64\times 4.0\) & 349 & 401 & 729 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: RHS members in tests and material properties [40; 41]. for this joint did not include any holes. Figure 8 shows the Von Mises stresses for the simulated K-joint when yielding was reached in some areas (on the left) and after large deformations (on the right). It can be seen that yielding started in the brace under compression above the weld and later spread to the chord. A second validation to confirm the suitability of the numerical model was carried out by comparing the maximum loads obtained by the model with the results obtained in the experiments for Tests 2 to 6 (Table 1). The model was adapted to the corresponding dimensions and material properties of the specific joints. Table 2 presents the maximum loads obtained from the tests and simulations for the purpose of comparison. The percentage of deviation, which had a mean value of 5.1%, is also included in the table. Figure 9 shows the comparison of these results. The two lines above and below the diagonal indicating complete concordance represent deviations of up to 10%. The small differences registered confirm the validation of the model. Figure 8: Von Mises stresses in the simulation of the K-joint. Figure 6: Curve compression force vs. indentation at point 1. Figure 7: Curve compression force vs. indentation at point 2. The proposed numerical simulation did not include any initial cracks, and therefore, the occasional tensile failure in the braces or welds cannot be precisely simulated in terms of whether there are any defects or discontinuities that might lead to fracture. This limitation is typically assumed when these types of joints are modeled [39]. However, the other failure mechanisms (yielding and local buckling at the joint location), which can be grouped together under 'brace failures' or 'brace effective width failures', were well reproduced.