# The Resistance of Welded Joints of GAlvanized RHS Trusses with Different Vent Hole Geometries
## 5 Conclusions  
In this research, a FE model was successfully validated on the basis of experimental results and then extended to be able to analyze the behavior of RHS K- and N-joints in lattice girders when the brace members include the ventilation holes necessary for the hot-dip galvanizing process. Different vent hole shapes, which allow the recovery of fluid after the zinc bath, were evaluated in order to achieve good efficiency during galvanization. Complete recovery is only possible when the welds connecting the brace and the chord are cut by the orifices. This work is focused on joints prone to failure due to local buckling in the brace member at the joint location (effective width failure at the compression brace) and chord plastification. The following conclusions may be drawn from this study:  
* The developed FE simulation accurately reproduced the actual behavior of the analyzed joints, showing good agreement with the experimental results when the welds were modeled. Therefore, this model, based on shell elements, is adequate for simulating the RHS K- and N-joints in lattice girders and for predicting the strength and stiffness when fracture in welds can be avoided. * There is a reasonable agreement with the Eurocode equations, confirming that FEA is a useful tool for obtaining appropriate results regarding joint behavior. * In the numerical simulation, different combined failure modes were observed, but these were never dependent on the presence of a vent hole or on the shape of the vent hole. * The local buckling present in a brace failure occurs away from the vent holes and the welds; therefore, in these cases, the presence of holes has no influence on joint resistance. * If the thickness ratio between the brace and the chord results in chord plastification, the effect of the presence of a hole is also negligible with respect to joint resistance. * The presence of a ventilation hole for the hot-dip galvanizing process such as those considered in this study does not significantly affect the joint resistance. * Based on the small differences observed for joint resistance, it is possible to affirm that it does not matter what type of vent holes are used for the galvanization process. All the analyzed hole shapes presented fair performance in terms of the mechanical strength of the joint. Although the  
Figure 16: Failure in joint NP10 with V-notched hole and braces angles of 45–90\({}^{\circ}\). Figure 15: Failure in joint KC8 with V-notched hole and brace angles of 60\({}^{\circ}\). shapes that cut the brace-chord weld exerted slightly more influence over the resistance than holes at some distance, all of them could be proposed to be valid solutions for machining vent holes. Taking into account the above-mentioned conclusions, we can offer some recommendations for engineers when designing galvanized lattice girders with RHS. They may choose any of the considered vent hole configurations, observing only the suggested filling areas. Therefore, certain preferences throughout the manufacturing process could be reasons for making a final decision. This research work, carried out as part of a Cidect project, was discussed, reviewed and approved by the group of experts in the Cidect Technical Commission. Conceptualization, M.A.S. and C.L.-C.; Methodology, C.L.-C. and J.S. ; Validation, F.L.G. Formal Analysis, C.L.-C. and F.L.G. ; Writing--Original Draft Preparation, M.A.S. and T.W. ; Writing--Review & Editing, M.A.S., T.W. and J.S. ; Funding Acquisition, M.A.S. This research was funded by Spanish MINISTERO DE CIENCIA E INNOVACION, grant number BIA2017-83467-P, by the Cidect under project 5 BX and by the European General Galvanizers Association. The authors would like to acknowledge the IEMES Research Group from the University of Oviedo and the CASE from the University of Sydney for their backing. Besides, they would also like to thank Swanson Analysis Inc. for their assistance with the use of ANSYS University program. \"The authors declare no conflict of interest\".