Compressive performance of bamboo scrimber and concrete-filled steel tube columns

The light and high strength bamboo scrimber was buried in the core of concrete-filled steel tube (CFST) to form bamboo scrimber and concrete-filled steel tube column (BCFST), which was expected to reduce the amount of concrete and weight in CFST and promote the use of bamboo scrimber. To investigate the influences of key design parameters on the compressive performance, namely bamboo scrimber dimension, design concrete strength, and diameter to thickness of steel tube, ninety BCFSTs and eighteen CFSTs specimens were tested under axial compression. According to the experimental results, the improvement of the BCFST bearing capacity resulted from the contribution of the inner sandwich concrete and the bamboo scrimber under the constraint from the steel tube. The ultimate load rose with the increase of the bamboo scrimber dimension, concrete strength, and steel tube thickness. Note that the increase range of ultimate load of BCFSTs is 3.9% higher than that of CFSTs by increasing the dimension of bamboo scrimber, with a maximum increase at 43.9%. The damage modes of BCFSTs can generally be categorized into local buckling failure mode and shear failure mode. In addition, owing to the different compactness between the bamboo scrimber and the concrete, the stress-strain curve of the C80 concrete characterized the strain hardening tendency rather than the strain softening tendency in the C50 concrete. According to the load-strain curves of the BCFSTs and the contribution of the composite actions between the three parts of the member to the load-carrying capacity, the characteristic points were defined. A calculation model for accurately predicting the ultimate capacity of BCFSTs was proposed by considering the boundary conditions for both non built-in and fully built-in bamboo scrimber in CFSTs.