A novel biomass bamboo coarse aggregate concrete: Cyclic axial compression behaviour and modelling

This study pioneers in exploring the cyclic compressive behavior of bamboo coarse aggregate (BCA) concrete (BAC). BAC columns with BCA replacement rates ranging from 0 % to 45 % were tested, using either unmodified or epoxy mortar-modified methods. The evaluation focused on their cyclic compressive stress-strain relationship, failure modes, and the effects of BCA replacement rates and modification methods on plastic strain, stiffness and stress degradation, terminal strain on the reloading curve, and hysteretic energy dissipation. Research indicates that adding BCAs reduces concrete's peak stress but enhances its other cyclic mechanical behaviors, including improved ductility, stronger hysteretic energy dissipation, and lower degrees of performance degradation. Plastic strain in BAC is generally lower than in normal aggregate concrete (NAC) at the same unloading point strain, with BCA replacement rate and modification methods having negligible effects on plastic strain. Stiffness degradation decelerates as BCA replacement rate increases, and stress degradation lacks a clear trend, though it is more pronounced in unmodified BAC. Higher BCAs replacement rates lead to a slower decline in hysteretic strain energy over cycles, with hysteretic strain energy during decline surpassing that of NAC. Finally, the study establishes comprehensive cyclic compression stress-strain equations, providing a theoretical foundation and practical guidance for future BAC research.