Numerical model of dynamic response under low-velocity impact of SCC beams reinforced with GFRP and containing waste materials

Purpose This study aims to develop and validate a finite element model to simulate the dynamic response of sustainable self-compacting concrete (SCC) beams reinforced with glass fibre-reinforced polymer (GFRP) bars under low-velocity impact. The focus is on evaluating structural performance and energy dissipation when incorporating waste-based additives such as expanded polystyrene (EPS) beads and polyethylene terephthalate (PET) fibres. Design/methodology/approach Three SCC beams were tested under a 37.5 kg drop weight from 3.5 m: a steel-reinforced reference beam (SB), a GFRP-reinforced beam with EPS (GB1) and another with GFRP, EPS and PET fibres (GB2). A validated finite element model was developed in Abaqus/Explicit using the concrete damage plasticity (CDP) approach. The model included randomly distributed EPS voids and 1-D PET fibres. Parametric studies examined the influence of impact velocity and mass under constant kinetic energy. Findings The GB2 beam exhibited better energy absorption, higher ductility and reduced residual deformation compared to SB and GB1. It showed the largest area under both the force–time and displacement-time curves, indicating improved impact resistance and damping capacity. Crack analysis revealed that GB2 experienced faster but more uniformly distributed cracking, while SB showed fewer but wider cracks. Damage visualisation confirmed that failure in GB2 was gradual and distributed, with peak tension damage occurring at 0.010 ms, compared to 0.008 ms in SB. Stress analysis highlighted the role of PET fibres in bridging cracks and maintaining load transfer after peak loading. The finite element model accurately replicated experimental behaviour in terms of force response, deflection, and crack propagation. The parametric study demonstrated that increasing impact velocity from 1.0 to 4.0 m/s increases the displacement from 1 mm to 6 mm and results in a more severe, localised failure pattern. In contrast, reducing the mass from 0.58 kg to 9.25 kg caused a broader deformation zone and reduced oscillations. These results confirm that, despite equal kinetic energy, impactor mass and velocity have distinct effects: high-velocity impacts induce sharper force peaks and brittle responses, while high-mass impacts promote more stable, ductile failure mechanisms. Originality/value This study presents a validated numerical model for predicting the behaviour of SCC beams reinforced with GFRP bars and waste-based materials under impact loading. It highlights the importance of how impact energy is applied and shows that adding EPS beads and PET fibres improves energy absorption and delays failure.