Transverse impact behavior of novel iterative pultruded-wound GFRP bars: Experimental investigation and FE analysis

Fiber-reinforced polymer (FRP) bars have been developed as a corrosion-resistant alternative to traditional steel reinforcement. However, conventional pultruded glass FRP (GFRP) bars exhibit poor transverse impact resistance due to their unidirectional fiber orientation, and studies on effective enhancement strategies remain limited. This inherent vulnerability imposes constraints on the broader application of FRP bars in real applications. To address this issue, this study proposes a novel iterative pultruded–wound GFRP bar fabricated through a multi-stage pultrusion and winding process, aiming to significantly improve impact resistance and durability. The mechanical performance of the proposed bar was evaluated through comprehensive experimental tests and finite element simulations. Results show that, compared with traditional GFRP bars, the new design increases energy absorption by 238.1 % and improves impact ductility by 40.6 %. The optimized combination of circumferential and longitudinal fibers shifts the failure mode from interlaminar delamination to fiber fracture, thereby enhancing structural integrity. A finite element model was also developed to investigate the effect of impact velocity. Parametric analyses reveal that increasing the number of circumferential fiber layers enhances impact resistance, but the improvement decreases beyond a certain point.