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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. • Bamboo scrimber and concrete-filled steel tube (BCFST) columns were presented. • Influences of bamboo ratio, concrete strength and steel tube thickness on BCFST columns were examined. • The stress-strain curve of BCFST showed two trends of strain softening and strain hardening. • Strength model considering composite action of concrete, bamboo and steel tubes was proposed. [ABSTRACT FROM AUTHOR]

Bamboo fiber (BF) possesses advantages such as environmental friendliness, renewability, economic viability, and favorable mechanical properties, making it a promising material for improving the brittleness and tensile strength of concrete. Previous investigations have demonstrated a limited exploration of BF-reinforced lightweight aggregate concrete (LWAC). Current study concentrates on investigating the mechanical properties and stress-strain relationship of BF-reinforced LWAC. To achieve this, 7 groups of BF-reinforced LWAC specimens were subjected to compressive tests, splitting tensile tests, and prism compressive tests. The influence of BF content and length on the compressive performance, failure modes and stress-strain curves was studied. BFs effectively suppressed the development of internal cracks in LWAC, playing a role in crack resistance and toughness enhancement. Furthermore, BFs significantly improved the splitting tensile strength of concrete, while the compressive strength slightly decreased with the increase of BF content. After adding BFs, the splitting tensile strength of concrete increased by 8.2∼23.7%, and the compressive strength decreased by 3.6∼11.1%. Moreover, the BF length had almost no effect on the compressive strength of concrete, while when the BF length was 10–30 mm, the tensile strength increased by 5.3∼17.6%. Based on existing researches, strength conversion equations and stress-strain constitutive models of BF-reinforced LWAC were proposed, and the models provide a theoretical basis for the calculation and analysis of BF-reinforced LWAC components and structures. • Bamboo fiber (BF)-reinforced lightweight aggregate concrete (LWAC) was examined. • BFs significantly improved the splitting tensile strength and ductility of LWAC. • The failure modes of specimens were analyzed based on SEM images and DIC technology. • The stress-strain models of BF-reinforced LWAC were established. [ABSTRACT FROM AUTHOR]