# The Resistance of Welded Joints of GAlvanized RHS Trusses with Different Vent Hole Geometries
## 1 Introduction
More specifically, in truss joint design, where the joint resistance typically governs the selection of hollow section members, any superior compressive resistance achievable by hot-finished products is frequently not utilized. Furthermore, protection against corrosion and welding around the corners of brace members when they are welded to the chord of the lattice girder is easier to achieve in cold-formed sections due to their smoother corner radius. In the same way, according to [16], the manufacturing method, hot-finished or cold-formed, is not the fundamental factor dictating the properties of hollow sections. [PERSON] [16] studied the suitability of cold-formed tubes for structural applications, and specifically considered the suitability of these products to be hot-dip galvanized due to their potential risk of corner cracking, which is sometimes associated with this protection process. The conclusion of this publication was that properly made cold-formed hollow sections do not have a tendency to LME (liquid metal embrittlement), and corner cracking and hot-dip galvanizing do not essentially alter the strength or the ductility of the hollow sections. Therefore, welded structures made of cold-formed hollow sections can be safely protected using the hot-dip galvanizing process. According to the European General Galvanizers Association (EGGA) [17; 18], the use of galvanization in Europe is strong, and exhibited an increase of about 25% within a period of 15 years, reaching a maximum of nearly 7.0 million tons in 2008. After that peak in production, and as a consequence of the economic crisis in Europe, there was a reduction of around 7%, since when the prospects in major European countries have not been so encouraging. Nevertheless, it is hoped that further market penetration against painting of steel will continue. Researchers studying the effect of hot-dip galvanizing on steel properties have concluded that the effect of the process on the main mechanical properties, such as yield limit, is almost negligible [19]. As a result, the standard specifications (ASTM A924 and EN10142) calculate the yield and tensile strengths for hot-dip coated steel using the base steel thickness only [20]. Although pre-galvanizing countermeasures should be considered to avoid cases of brittle cracking resulting from hot-dip galvanizing on cold-formed tubes [21; 22], when the process is carried out correctly, this embrittlement effect has been found to be negligible, even in hot-dip galvanized welded joints submitted to fatigue loads [23]. Together with all the previous statements, we can assume that the heat-affected zone (HAZ) in structural steel, and particularly in HSS, does not affect the welded joint behavior [24]. According to the previous paragraphs, the main gap of knowledge with respect to hot-dip galvanized trusses with hollow sections is the effect of the vent holes on the resistance of the welded joints, since most of the other effects of the zinc bath are negligible when the process is performed correctly. Some research has been carried out in the framework of two projects [25; 26] funded by the CIDECT (Comite International pour le Development et l'Etude de la Construction Tubulaire) and the EEGA (European General GAlvanizing Association). In [25], after a deep literature review, the authors suggested the most appropriate sizes, shapes and positions of ventilation holes, although they did not study joint resistance. In [26; 27], a study based on an extensive experimental program and subsequent finite element analysis studied whether or not the circular holes recommended in [25] produced a reduction in the joint resistance of different configurations of typical welded truss joints involving RHS with gaps between the braces. The main result suggested that the considered vent holes had a very small effect on the joint strength. In that research, circular holes located away from the chord face were considered.