Experimental Study On Fatigue Performance Of CFRP Composite Composite Anchor

CFRP tendons have become a potential replacement for bridge cables due to their excellent properties,but their lateral shear resistance limits their large-scale use.At present,the anchors mainly developed are mainly bonded,clip-type and composite.Bonded anchors can better prevent transverse shear failure of the ribs,but the volume is too large to limit its use,and the clip-type anchors are easy.The sandwiching of the tendons and the composite anchors combine the advantages of both,and the research value is huge.At present,the research on composite anchorage mainly focuses on the study of static performance,and there are few studies on its fatigue performance.This paper is an experimental study of CFRP-reinforced composite anchors under fatigue loading.Comparing with quartz sand,iron powder and aluminum powder reinforced adhesive,it is tested that the quartz sand reinforced adhesive is the best as the bonding material of the anchor.The structural response of the composite anchor under cyclic loading was analyzed in terms of system slip,casing strain,temperature rise in the anchorage zone,residual tensile load capacity and stiffness degradation.The results show that the maximum stress level and stress ratio have a significant effect on the fatigue performance of composite anchors.Cyclic loading with high stress ratios and low stress levels can promote synergistic effects between the components of the anchor.However,increasing the stress level or lowering the stress ratio results in greater slippage,greater damage,and more cyclic loading of the composite anchor into a steady state.When the stress ratio exceeds 0.4 and the maximum stress is less than 0.5,the damage in the anchorage zone begins and develops in the early stage of cyclic loading,but eventually the anchor tends to be stable.A large drop in the stress ratio may result in the continued development of microstructural damage and the ultimate failure of the anchor,with increasing energy dissipation under cyclic loading.The axial strain of the sleeve in the composite anchor is affected by the degree of damage evolution and the synergistic effect of the anchor assembly,resulting in different trends of the strain-cycle curve of the anchor sleeve under different stress ratios and stress levels.For anchors with infinite life,a trilinear curve of stiffness and circulation was found,while an approximately linearly reduced stiffness-cycle curve of the failed anchor was observed under cyclic loading.The fatigue life of composite anchors was analyzed by finite element method.The static analysis of anchors was carried out by Abaqus.The fatigue analysis based on finite element analysis and FE-safe software was used to predict the fatigue life of anchors.Comparing the life results,the fatigue life is relatively consistent,which provides a basis for the optimization design and fatigue life prediction of composite anchors.