Modal analysis of concrete filled steel tubular structure under lateral impact loading

Abstract

In this paper, deformation mode and the large deflection of the concrete filled steel tubular (CFST) structural member with fixed ends under lateral impact loading was studied by rigid-plastic modal approximation method and finite element analysis by ABAQUS. Using the yield criterion and beam-on-foundation model, the modal analytical solution for plastic behavior of CFST member under lateral impact is obtained considering the interaction of bending and axial stretching. The rigid-plastic modal solution captures the FE results and the deformation mode is accordance with the available experimental results. It shows that lateral deformation of CFST member can be effective predicted by the modal solution consisting of geometric and physical parameters variations. The influence of steel tube thickness, cross-section diameter, effective length, strength and density of concrete and steel, and initial impulsive are discussed in detail. The results show that deflection of the CFST member increase with the increase of the length to diameter ratio, initial impulse and smaller thickness to diameter ratio. Finally, the relationship between lateral deformation and geometric variations are established by optimal sets of modal solution.