Abstract
A total of eight weld plate-reinforced steel plates were tested under loading applied through self-weight and leverage to investigate the coupling effects of preload and welding heat on the global buckling behavior of compressed steel plates, considering the initial stress ratio, the presence of a weld plate, and the weld to reinforced plate thickness ratio. The temperature field exhibited an elliptical distribution, with a major-to-minor axis ratio of approximately 3:1 in regions exceeding 600 °C. The high-temperature penetration area(>600 °C) on the back side was 11 % of that on the front side. Strain evolution within the weld zone was controlled by the welding temperature, while the strain evolution outside the weld zone was influenced by initial stress ratio. The gradual compatibility between the weld plate and the reinforced plate caused an arching rebound phenomenon, which reduced with preloading and disappear entirely when initial stress ratio (n) reaches 0.64. A finite element model considering the welding process was established, and a multi-layered validation approach—covering molten pool morphology, temperature penetration area, and time-deflection curves—was proposed. The mechanism of global buckling behavior due to thermo-mechanical coupling includes three components during the welding and cooling process under load: eccentric pressure within the cross-section caused by uneven cooling shrinkage, increased local stiffness of the weld plate, and the P-Δ effect. Recommendations for welded reinforcement are proposed to reduce deflection deformation and enhance structural performance.