Ultimate bearing capacity and multi-scale optimization design of a novel palm-shaped joint in steel structures

To investigate the mechanical properties and ultimate bearing capacity of complex steel structural systems, this study examines a novel palm-shaped joint used in the spatial grid and truss composite structure of the Guangzhou Baiyun International Airport Phase III Hangar Project. Axial compression tests were carried out on a 1:3 scaled model, complemented by finite element simulations conducted in Abaqus. The results demonstrate that the joint failure is primarily due to out-of-plane buckling of specific steel plates, with an ultimate bearing capacity approximately 3.1 times the design load, indicating a considerable safety reserve. The tube wall thickness and overlap ratio are identified as key factors affecting joint strength, whereas the inclination angle between the supporting member and the chord shows negligible influence. An improved design formula is proposed based on parametric studies, offering significantly enhanced accuracy over current design codes. Additionally, a multi-scale optimization design scheme incorporating longitudinal stiffeners is introduced, which leads to a 13.7% reduction in maximum stress and a 39.55% decrease in displacement under ultimate loading conditions, markedly improving the joint’s mechanical performance. The findings offer valuable insights for the optimized design of complex joint systems in contemporary steel structures.