Study on the mechanical behavior of the connection interface in steel–timber box composite member

This paper proposes a novel box steel–timber composite member , and investigates its mechanical behavior under different types of interface connections. A total of 18 push-out specimens divided into four groups were tested. During the testing process, the XTDIC three-dimensional digital image correlation (DIC) system . Furthermore, finite element analysis was conducted to propose the optimal interface connection configuration. The results indicate that: The stud radius exhibits a positive correlation with the ultimate load, while the stud material primarily affects stiffness. Its influence on the ultimate load shows a positive correlation with the stud radius. An optimal balance is achieved when the stud spacing is 150 mm ; The epoxy resin adhesive connection exhibits brittle interfacial failure, and the bonding length is positively correlated with the mechanical performance; The stud–epoxy-resin composite connection significantly enhances the structural stiffness and ultimate load, and the failure mode transforms into ductile failure; In the composite system incorporating reinforcing steel plates, the 2.0 mm steel plate weakens the anchorage effect of the studs, resulting in brittle failure, whereas the 1.0 mm steel plate significantly enhances the structural stiffness and ultimate load, leading to ductile failure. The performance of polyurethane adhesive is markedly inferior to that of epoxy resin adhesive. Parametric optimization indicates that a reinforcing steel plate thickness of around 0.6 mm is suitable only for stiffness control, while a thickness of around 1.0 mm achieves an optimal balance between stiffness, ultimate load, and economic efficiency.