# Axial Compression Behavior of Bamboo Scrimber-Filled Steel Tubular (BSFST) Column Under Different Loading Modes

## TL;DR

This study examines how steel tubes improve the compression strength of bamboo columns under different loading conditions.

## Contribution

A novel bamboo scrimber-filled steel tubular column is introduced, showing enhanced structural performance through steel confinement.

## Key findings

- Steel tubes significantly increase the load-bearing capacity and deformation capacity of bamboo columns.
- Core-loading specimens outperformed full-section-loading specimens in both load-bearing and deformation.
- Predictive models for ultimate stress and strain were developed with high accuracy.

## Abstract

Bamboo scrimber is an environmentally friendly biomass building material with excellent mechanical properties. However, it is susceptible to delamination failure of the transverse fibers under compression, which limits its structural performance. To address this problem, this study utilizes steel tubes to encase bamboo scrimber, forming a novel bamboo scrimber-filled steel tubular column. This configuration enables the steel tube to provide effective lateral restraint to the bamboo material. Axial compression tests were conducted on 18 specimens, including bamboo scrimber columns and bamboo scrimber-filled steel tubular columns, to investigate the effects of steel ratio and loading mode (full-section and core loading) on the axial compression performance. The test results indicate that the external steel tubes significantly enhance the structural load-bearing capacity and deformation capacity. Primary failure modes of the composite columns include shear failure and buckling. The ultimate stress and strain of the structure are positively correlated with the steel ratio; as the steel ratio increases, the ultimate stress of the specimens can increase by up to 19.2%, while the ultimate strain can increase by up to 37.7%. The core-loading specimens exhibited superior load-bearing capacity and deformation ability compared to the full-section-loading specimens. Considering the differences in the curves for full-section and core loading, the steel tube confinement coefficient was introduced, and the predictive models for the ultimate stress and ultimate strain of the bamboo scrimber-filled steel tubular column were developed with accurate prediction.