English：

Taking Q355 low alloy steel structure nodes as the research object, a mechanical equilibriummodel considering material nonlinearity and geometric nonlinearitywas constructed. Combined with thenode deformation compatibility conditions, the influence mechanisms of key parameters such as platethickness ratio, pretightening force and bolt spacing on node bearing capacity, stiffness and stressdistribution were systematically analyzed. The research results show that the node bearing capacityincreases linearlywith the increase of the plate thickness ratio. It is recommended that the plate thicknessratio be between 1.0 and 1.5 to balance safety and economy. The pretightening force loss changesnonlinearly in stages with the slip amount. When the slip amount exceeds the critical value of 0.645mm,the pretightening force loss tends to stabilize. It is suggested that the working slip amount be controlledwithin 0.6mm. The bolt spacing ratio significantly affects the degree of stress concentration and stiffnessrecovery. When bolt spacing ratio is between 3.0 and 3.5, the stiffness reduction coefficient can riseback to above 0.97, and the overall mechanical performance is optimal.