Experimental-numerical study on axial compression performance of square concrete columns confined by new-type BFRP

Facing the substantial protection requirements for reinforced concrete structures exposed to severe erosion conditions, a novel composite material(Basalt Fiber Reinforced Polymer, BFRP) based on epoxy silicone resin as a matrix was introduced in this study. This material exhibits notable enhancements in resistance to acid and alkali corrosion, ultraviolet irradiation, as well as high and low temperature extremes. However, it exhibits lower elastic modulus and higher ductility. To evaluate the effectiveness of this new BFRP composite material in reinforced concrete structures, a comprehensive investigation was conducted by model testing, numerical simulations, and theoretical analysis. This study analyzed the impact of wrapping configuration, number of wrapping layers, concrete strength, and spacing-to-bandwidth ratio on the mechanical properties of concrete square columns. The findings revealed that the loading curve trends for specimens reinforced with the new BFRP sheet and CFRP sheet (Carbon Fiber Reinforced Polymer, CFRP) were almost similar, although the reinforcement effect was comparatively worse for the former. When both layers were fully applied, the axial compression bearing capacity increased by 28.45% and 64.73%, respectively. The number of wrapping layers and the parameters related to concrete strength significantly influenced the reinforcement effect, whereas the influence of spacing-to-bandwidth parameters was less pronounced. Current specifications demonstrate suitable applicability for CFRP-reinforced specimens but limited applicability for BFRP. The calculation model proposed in this paper accurately predicted the axial compression bearing capacity of a new BFRP-reinforced columns, with an error margin kept within 5%.