To clarify the presence or absence of local buckling suppression effect and confining effect due to the interaction between the metal pipe and the wood, a short column test was first conducted by simultaneously compressing both the wood and pipe sections of a square steel tube with knotty wood inserts. The results showed that the relationship after reaching the maximum compressive force between compressive stress and strain in these short columns under the conditions of this experiment is a superposition of the relationships obtained in tests with only the steel tube and only the wood. Following this, a short column test was conducted using a method where the compressive force was applied directly only to the knotty wood inserted in square steel and aluminum square tubes. Consequently, there was no confining effect of each metal tube on the compressive strength of the knotty wood. Simultaneously, a confining effect on behavior during the stress descending portion was observed.
