Dynamic response and parameter analysis of concrete-filled steel tubular structure under lateral impact loading

By employing the mode approximation method for rigid-plastic structural dynamic behavior and numerical simulation, a dynamic response analysis was conducted on circular-section concrete-filled steel tubular (CFST) structures subjected to lateral impact loadings. The mechanical model of the CFST structure was equivalently represented as a rigid-plastic foundation beam model according to its plastic behavior. Under the linear velocity field assumption and the geometric similarity, the equivalently initial velocity for mode approximation of the structure was derived and compared with the existing experimental data. An analytical solution for the plastic lateral deformation at the mid-span of the CFST with two fixed ends by the rigid-plastic mode approximation method was provided, yielding non-dimensional geometric and physical parameters that influenced the ultimate lateral plastic deformation. A numerical model of the CFST structure under lateral impact was established using ABAQUS/Explicit. The theoretical and numerical predictions were both compared with existing experimental global deformations. Dimensional analysis and numerical modeling were combined to analyze the geometric and physical parameters, as well as the initial impact impulse, which influence the plastic deformation of the CFST structure. The results demonstrate a good agreement between the theoretical, numerical results, and experimental data, confirming that the plastic deformations of the structure align with the assumed distribution of plastic hinges. For geometric variables, the ratio of length to diameter and ratio of thickness to diameter exert a significant influence on the final lateral deformation. The relative width of the indenter can alter the deformation shape of the structure. The physical parameters of the steel tube and core concrete have less impact on the deflection at the mid-span compared with the geometric variables. The final lateral deformation of the CFST structure exhibits a quadratic correlation with the initial impact impulse. Finally, the applicable range of all the theoretical analysis variables is given according to the corresponding parameter analysis. The proposed mode solutions for rigid-plastic response provide a reliable prediction of the plastic deformation behavior of the CFST structures under lateral impact loadings.