Elastic local buckling of double-skinned UHPC composite plates considering interfacial shear slip

This study explores the elastic local buckling behavior of double-skinned ultra-high-performance concrete (DS-UHPC) composite plates, focusing on the effects of interfacial shear slip. A theoretical model, based on the first-order shear deformation theory for sandwich plates, was developed to predict the elastic local buckling behavior of these composite plates. An analytical solution for the elastic buckling coefficient under uniform compression with a simply supported boundary condition was derived. The results reveal that interfacial shear stiffness and the proportion of cross-sectional steel content significantly affect the elastic buckling coefficient. Specifically, lower interfacial shear stiffness and higher steel content proportion result in a decreased buckling coefficient, while increasing interfacial shear stiffness reduces the sensitivity of the buckling coefficient to variations in steel content proportion. Finite element models were established and validated against previous studies on the buckling performance of single-layer steel-concrete composite plates and classical solutions of buckling coefficients without interfacial shear slip. Semi-analytical solutions for the elastic buckling coefficient under various boundary conditions were also developed through a comprehensive set of finite element results. Building on these findings, a design procedure for DS-UHPC composite plates is proposed, emphasizing the optimization of interfacial connectors to minimize shear slip effects on local buckling. This procedure ensures the prevention of local buckling in both the external steel plates and the entire composite plate, thereby enhancing structural stability.