Finite element model analysis of long-term performance of composite anchorage based on double-material parameters

Carbon fibre-reinforced polymer (CFRP) tendons demonstrate the advantages of light weight, high strength, and superior corrosion resistance and have broad application prospects for longspan cable structures. However, given the low transverse shear strength of CFRP tendons, how to achieve long-term and reliable anchorage for CFRP tendons is a critical issue. The long-term performance (LTP) of a novel composite anchorage for CFRP tendon was assessed in this study. Then, a finite element model (FEM) with double-material creep parameters was established to reliably model the LTP experiment according to the creep parameters of the bonding medium and CFRP tendon. Finally, the effects of the free section tendon length, pre-tightening force, overtensioning force, and elastic modulus of the bonding medium were analysed using the established FEM with double-material creep parameters. Results revealed no visible damage to the CFRP tendon and anchorage after the LTP experiment. The maximum tendon slippage was 0.054 mm, and the residual load ratio was 0.826. These phenomena indicate that the novel composite anchorage has excellent LTP. The FEM modelling results based on double-material creep parameters were in good agreement with the experiment results. The residual load ratio calculated by the FEM was 1% lower than the experimental value. Through the parameter analysis, the residual load ratio of the specimen was effectively improved under longer free section tendon condition, but tendon slippage increased to a certain extent. In addition, the LTP of the composite anchorage can be effectively improved by appropriately decreasing pre-tightening force and overtensioning force. When the over-tensioning force was 1.4 times the test load, the tendon slippage was reduced by 34.2%, and the residual load ratio increased by 4.8%. The greater elastic modulus of the bonding medium in the range of 2.1 GPa-3.1 GPa, the worse the LTP of the composite anchorage.