Impact resistance of flax FRP fully wrapped coconut fibre reinforced concrete beams and shear contribution of FRP

This study investigates the behaviour of flax fibre reinforced polymer (FFRP) fully wrapped coconut fibre reinforced concrete (CFRC) beams and FRP contribution to shear strength under impact loadings. Both repeated and single drop-weight tests were carried out on the beams, with a dimension of 500 mm x 100 mm x 100 mm and three different FFRP wrapping thicknesses. For the repeated impact tests, the impact reaction force, deflection histories and FRP strains were recorded and analysed to investigate the influence of FFRP wrapping thickness on the impact resistance. For the single impact tests, the energy absorption, failure modes and the shear contribution of FFRP in CFRC beams was studied. The results showed that the impact resistance of the fully FFRP wrapped beams showed a non-linear increase tendency with thickness. The damage mechanism of concrete beams is also influenced by the FRP thicknesses. The analytical results of shear contribution of FFRP were calculated by considering the dynamic increase factor, which fits well with experimental values, indicating that the proposed method is reasonable.

Automated summary

This study investigates the behavior of fully wrapped coconut fiber reinforced concrete (CFRC) beams reinforced with flax fiber reinforced polymer (FFRP) and the contribution of FRP to shear strength under impact loadings. Both repeated and single drop-weight tests were carried out on beams with three different FFRP wrapping thicknesses. The results showed that the impact resistance of fully FFRP wrapped beams increased nonlinearly with thickness. The damage mechanism of concrete beams and the shear contribution of FFRP in CFRC were also influenced by the FRP thicknesses. The proposed method of calculating the shear contribution of FFRP fit well with experimental values.