Static and dynamic axial crushing of prismatic thin-walled metal columns

In this paper, a novel approach is proposed to investigate the progressive collapse damage of prismatic thin walled metal columns with different regular cross sections, under the action of axial quasi-static and impact loads. The present work mainly focuses on implementation of some important factors which have been neglected in other studies. These factors include the effect of reducing impactor velocity and inertia effect during collapse, a mixed collapse mode for crushing mechanism, and consideration of a realistic elasto-plastic model for material. Taking all these factors into account, the analysis led to some parametric algebraic equations without a possible general solution in terms of collapse variables. Consequently, a new theoretical approach was proposed based on previously offered Super Folding Element (SFE) theory, to obtain the closed form explicit relations for the static and dynamic mean crushing forces and collapse variables. The proposed approach considers an analytic-numeric discretization procedure to solve these equations. To evaluate the results, a detailed finite element analysis on square mild steel models was conducted under an axial impact load, using LS-DYNA and ANSYS software programs. Comparison of the experimental results that are available in the literature with those of finite element analysis, shows the applicability of this approach in predicting the collapse behavior in such structures.