Dynamic response, buckling and collapsing of elastic-plastic straight columns under axial solid-fluid slamming compression—I. Experiments

Abstract

The dynamic behavior of straight elasto-plastic columns subjected to axial solid-fluid slamming compression is investigated experimentally in the present study. Two classes of columns are tested: large slenderness columns with the static Euler strain εcrE smaller than the yield strain εy and middle slenderness ones with the εcrE close to the εy. Three critical conditions for each of the columns are observed from the experiments: plastic incipience, buckling, and plastic collapse. These conditions are defined by introducing three critical loading strains: plastic, buckling, and collapse axial loading strains. The three critical strain values for each tested column are reported in the paper. The results indicate that: (1) the plasticity in a column appears first at the center and the plastic region is always at the middle length; (2) according to the buckling definition, the type 1 columns buckle elastically while the type 2 buckle plastically: (3) the column's load-carrying capacity is insensitive to the elasto-plastic loading histories (sequences) which the structure experiences before the plastic collapse occurs and is essentially governed by the dynamic post-buckling elasto-plastic behavior in one slamming: and (4) at the critical buckling loading magnitudes the column's response becomes dominated by motion in the fundamental mode.