Finite Element Simulation Of Concrete Beams Strengthened With CFRP Anchors

Carbon Fiber Reinforced Polymer(CFRP)is widely used in concrete reinforcement due to its characteristics of lightweight,high strength,and good corrosion resistance.A series of researches on concrete tests with CFRP have been conducted.However,these researches mainly focused on the analysis of axial compression,bias,bending,shearing and seismic performance of the members,but there are few studies on concrete specimens strengthened with CFRP anchors,the finite element models and related analysis of concrete beams strengthened with CFRP anchors are more limited.In order to fully understand the mechanical properties of concrete beams strengthened with CFRP anchors,a new finite element model was proposed in ANSYS to simulate the concrete beams.Through comparison with the Sun model and his test results,it is proved that the new model has better accuracy and applicability,the specific research contents are as follows:Firstly,this paper makes a comprehensive analysis of the exiting Sun model and finds that there are deficiencies about geometric models and material models in this model.Based on ANSYS,a full consideration of various factors and more realistic finite element model(hereinafter referred to as the complete model)is proposed.Compared with the Sun model,the modeling method of concrete and CFRP anchor at the anchor hole is improved and through comparison with Sun's test results,it is proved that the complete model has good simulation results.In addition,the stress distribution of CFRP anchor at the anchor hole is simulated by placing contact pair between CFRP anchor element and concrete element,and it's found that CFRP anchor fracture failure is most likely to occur on the CFRP anchor at the edge of the anchor hole.Secondly,for the sake of simplicity in modeling and calculation,based on the proposed complete finite element model,a simplified modeling of the concrete and CFRP anchors at the anchor hole is carried out to obtain a simplified finite element model,the simplified processing includes:(1)The CFRP anchor with curved shape is made into a vertical shape and shares its nodes with the nodes of CFRP fan anchor and the CFRP anchor embedded in concrete.(2)The actual stress conditions are simulated by merging the CFRP anchor element nodes with the node in front of the concrete element but not merging with node at the back of the concrete element in ANSYS.(3)A suitable simplified elastic modulus E_s is set for the concrete at the anchor hole to control the concrete strain and deformation to an acceptable range in the simplified model.The model resultults are compared with the Sun model and his test results after the above treatment.According to the obtained data,the model has the advantages of low computational cost,reliable results and strong applicability.Finally,the simulation results obtained by simplified model are compared with the experimental and simulated results of Sun.The comparison contents mainly include the results of load-deflection curve,CFRP strip strain at Mid-span,CFRP strip strain at anchor fan end,anchor fan end strain and middle of anchor strain.The comparison results show that compared with the Sun model,the simplified model presented in this paper is more convenient for modeling and calculating the interface adhesion and it can well simulate the ultimate load when CFRP strip fractures.Moreover,this model also shows good accuracy and applicability when analysing the strain of CFRP strip.Through the above data,it is proved that the simplified model is more simple,efficient and accurate than the Sun model for the simulation of concrete beams strengthened with CFRP anchors.The simplified model has important theoretical and practical significance and can also help further research on the work of anchoring parameters and anchoring performance.