## 5 Conclusions  
The most outstanding conclusions are outlined below:  
* The obtained force failure values are compatible with the requirements for the studied type of assembly. The extensive variation in stacking conditions as well as lifting mechanisms commonly deployed in situ influenced the load nature on the joints. No known standard specification is available, as the strength of these welds is not part of the structural engineering design. In this study, the maximum values obtained by fusion welding were between 9800 and 29,400 N depending on the joint thickness. Comparing the breaking values obtained in joints of the same order of magnitude in our research tests with the obtained in the MIG welding, the results in both processes were the same [28].
* The cycle times utilized herein are not problematic as compared to those currently used in MIG-welding. The examined cases in this study employed welding cycles of less than two seconds. Extending that time would reduce the labor intensity.
* Working pressure should complement the melting conditions of the material. With lower thicknesses (lower resistance), the joint reached its melting temperature too early, and the pressure presence caused excessive damage to the joint. In the tests performed with greater thicknesses (higher resistance), the joints did not reach such high temperature values, thus reducing the joint damage.
* Electrical resistance welding (without material input) promotes a healthier work environment where workers do not need to wear eye protection and the hazards inherent in gas and melting materials are also avoided, as gas-generating sources are eliminated. By controlling the intensity and cycle times, the danger of molten material splashing is also avoided and, thereby, the need for protective clothing, which are both inherent in welding with input material.
* If the consumed electricity comes from renewable sources, this kind of welding process is even more sustainable, and ultimately contributes to a greater respect for the environment.
* Strong performance in assembly welding is directly related to the joint thickness. The welding parameters can be regulated by determining the thickness of the joint (A + B). The regulation must be focused on the electrical intensity and time. A pressure of 5 bars was sufficient to achieve correct connections in all the joint thicknesses studied.  
Conceptualization, [PERSON] and [PERSON]; methodology, [PERSON] and [PERSON]-[PERSON]; software, [PERSON]-S.; validation, [PERSON]-[PERSON], [PERSON]-[PERSON], P.M.L.-S. and M.M.-V.; formal analysis, [PERSON], [PERSON] and [PERSON]-S. and M.M.-V.; investigation, [PERSON] and [PERSON]; resources, [PERSON]-[PERSON] and [PERSON]; data curation, [PERSON], [PERSON], [PERSON] and [PERSON]; writing--original draft preparation, [PERSON] and [PERSON]; writing--review and editing, [PERSON], [PERSON], [PERSON] and [PERSON]; visualization, [PERSON] and [PERSON]; supervision, [PERSON] and [PERSON]; project administration, [PERSON] and [PERSON]; funding acquisition, [PERSON], [PERSON], [PERSON] and [PERSON]. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
All the authors are greatly indebted to the company Vigas-Mazo SA and to the regional government of La Rioja. The authors would also like to express their gratitude for the support of the University of La Rioja.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.