Crushing mechanical responses of natural wood columns and wood-filled composite columns.

• Mechanical behaviors are experimentally investigated for wood-filled columns. • Wood column with longitudinal grain orientation is better for energy absorption. • Synergistic effect can promote the energy absorption of wood filled columns. • The wood-filled aluminum column has high crushing force efficiency. Composite structures with high crushing characteristics are drawing great attention in the structural design due to their excellent lightweight and high strength. This paper aims to investigate mechanical responses of natural wood columns and wood-filled aluminum or carbon fiber reinforced plastics (CFRP) columns under axial crushing load. Parametric studies are performed on the material of the external wall, the grain orientations (longitudinal, tangential, and radial) and the growth rings' gradient of the wood (Toona Sinensis) by experimental test. Experimental results show that grain orientations of the wood and the material of the external wall have remarkable influences on the collapse mode and the crushing force, and the wood column with longitudinal grain orientation presents the best energy absorption. In addition, the plastic buckling process, collapse mode and crushing force response of wood-filled composite specimens are comprehensively investigated under axial crushing load. It is found that wood-filled aluminum composite columns present progressive collapse mode and higher crushing force level than wood-filled CFRP composite columns. Furthermore, the synergistic behavior between the external wall and wood filler is evaluated. This study offers insights on designing novel energy absorber with high crashworthiness capacity by applying novel wood fiber materials. [ABSTRACT FROM AUTHOR]