Research on Resistance Welding Process Parameters of Steel Skeleton in High-speed Railway Simply Supported Box Girders

Research purposes：Currently，the fabrication of steel skeletons for simply supported box girders in high-speed railway construction primarily relies on manual tying，which is inefficient and costly. To address this issue，the authors of this paper proposed an automated resistance welding process for steel skeletons for simply supported box girders，which can replace traditional tying methods to enhance manufacturing efficiency and reduce labor costs. However，this welding process can cause some damage to the steel bars，potentially leading to fatigue issues at the weld points under repeated vehicle loads. The purpose of this study is to experimentally investigate the effects of different welding parameters on the static tensile strength and fatigue performance of cross-welded steel bars in the steel skeleton，to determine the optimal welding parameters to ensure the performance of the steel skeleton. Research conclusions：（1）The failure modes of the steel specimens produced by resistance welding differ between static tensile tests and fatigue tests. In the former，failure occurs as the transverse short steel bar detaches from the long steel bar at the weld point，while in the latter，it manifests as the longitudinal long steel bar breaking at the weld point. （2）The relationship between the welding parameters and the static tensile strength and fatigue life of the specimens is not a simple linear one，with the presence of local extremum points.（3）Considering both static tensile strength and fatigue life，the N3 welding parameter set demonstrates the best performance. The corresponding effective current value is 11.5 kA，the peak current is 16 kA，the voltage is 0.6 V，and the welding time is 9 cycles.（4）The findings of this study can be applied to the resistance spot welding of steel skeletons in high-speed railway construction，promoting the efficient production and development of simply supported box girders. © 2024 Editorial Department of Journal of Railway Engineering Society. All rights reserved.