Analysis Of The Mechanical Performance Of Reinforced Concrete Columns Confined By CFRP Strips

As a new type of material,FRP has many advantages such as light weight,high strength,and corrosion resistance.It has been widely used in concrete structures in recent years.The use of CFRP strips to constrain the reinforced concrete column can not only make the structure show good corrosion resistance as a whole,but also make the concrete in a three-way compression state,which greatly improves the stress performance of the concrete.Studies have pointed out that under the same cloth consumption condition,CFRP strip restraint has better ductility than full-wrapped concrete,and strip reinforcement is more economical.As a structural form,reinforced concrete columns confined by CFRP strips have the advantages of good ductility,mechanical performance and ease of construction.Although there are still some researches on this kind of components at home and abroad,the research conclusions are not perfect.The immature theoretical system limits its application in engineering.In this paper,combined with the current situation at home and abroad,the finite element software ABAQUS is used to analyze the compression and hysteresis performance of CFRP strip-constrained reinforced concrete columns under various working conditions,which can provide references and basis for future actual projects.The research work of this paper includes the following aspects:1.The research results on the compression and hysteresis properties of FRP-confined concrete at home and abroad were reviewed and summarized,providing a theoretical basis for the next research topic.2.ABAQUS finite element software is used to establish a finite element model of reinforced concrete columns confined by CFRP strips.By being compared with the ultimate bearing capacity and stress-strain curve in the references,the error is within the allowable range,which verifies the correctness of the constitutive selection,contact relationship and simulation method of this model.3.47 finite element models of reinforced concrete columns confined by CFRP strips under different working conditions were established,the stress cloud diagrams,loaddisplacement curves and the ultimate bearing capacity of composite columns were analyzed under different eccentric distances,CFRP strip widths,and concrete strengths,so as to summarize the force law of the composite column.4.14 finite element models of reinforced concrete columns confined by CFRP strips under different working conditions were established,the hysteretic curves,energy dissipation coefficient and ductility coefficient of composite columns,etc,were analyzed under different axial compression ratios,number of CFRP strips,concrete strength,etc,so as to summarize the hysteretic performance law of the composite column.The research results show that during the entire compression process,as the load increases,the maximum stress will appear in the middle of the column,and as the eccentricity increases,the tension area at the cross section of the column will increase relative to the compression area.The ultimate bearing capacity and the eccentricity are obviously non-linear;in terms of bearing capacity alone,the effect of increasing the number of layers of CFRP strips is better than increasing the strip width by the same multiple.When there are too many layers of strips,the specimen will be brittle when it is broken.Therefore,it is not recommended to wrap more than three layers of CFRP strips in this article.When the axial pressure is relatively small,the plastic deformation ability of the specimen is stronger;as the axial pressure ratio increases,the energy dissipation capacity of the specimen becomes worse,and the seismic performance of the composite column decreases.However,when the axial compression ratio increases,the ultimate load-bearing capacity of the specimen has a certain increase.Considering comprehensively,it is reasonable to be controlled the axial compression ratio under the working conditions of this article within the range of 0.3～0.4.