Study On Bias And Seismic Behavior Of GFRP Pipe-Spiral Stirrup Composite Confined Concrete Column

FRP has the characteristics of light weight,corrosion resistance and high strength,but it is easy to be brittle and not conducive to stress.Spiral stirrups can effectively solve the problem of easy local buckling in the early stage of elasticity.It also restrains concrete members and improves its static force.performance.Therefore,compared with the single constrained concrete column member,the GFRP pipe-spiral stirrup composite confined concrete column(Concrete Column confined by GFRP Tube and Spiral Stirrups)is undoubtedly a kind of high-performance composite structure with significant research significance.This structure is a new combination structure composed of GFRP outer pipe,concrete filled in the pipe,and spiral stirrups built therein.This paper combines the current status of research domestic and overseas.Uses numerical simulation methods to analyze the bias and seismic performance of structural columns under different working conditions,providing a reference for future engineering practice and specification formulation.ABAQUS finite element software was used to carry out a detailed study of the GFRP pipe-spiral stirrup composite restrained concrete column structure.Numerical simulation analysis was performed on the members based on the correctness of the test.The strength of the concrete and the thickness of the GFRP pipe were analyzed through research The influence of factors such as the spacing of spiral stirrups on the mechanical performance of the column,to discuss the superiority of the column structure.The research work in this paper includes the following three aspects:1.By summarizing the research status and theoretical research on axial compression,bias compression and earthquake resistance of FRP confined concrete columns at home and abroad,the research structure in this paper is determined as the GFRP tube-spiral stirrup negative composite confinement concrete column structure,and a reasonable Specific parameters of GFRP pipes,concrete and steel bars.2.Based on the GFRP pipe-spiral stirrup composite constrained concrete column constitutive model.The comparative analysis with the existing experiments validates the modeling method selected in this paper and the material cost.The rationality of the selection of the structural relationship.3.Established 39 finite element models of GFRP pipe-spiral stirrup composite constrained concrete columns under different working conditions,and analyzed the different concrete strength,GFRP pipe thickness,stirrup spacing and eccentricity of structural columns under eccentric compression.Under the load-displacement curve and ultimate bearing capacity,the mechanical properties and deformation laws of structural columns are studied.4.Established 24 finite element models of GFRP pipe-spiral stirrup composite constrained concrete columns under different working conditions,and analyzed different concrete strength,GFRP pipe thickness,stirrup spacing and axial compression ratio under low-cycle cyclic loading.The influence law of its shear bearing capacity,energy consumption capacity,deformation capacity and stiffness degradation.It was found that in terms of eccentric compression,with the increase of the thickness of GFRP pipe and concrete strength,the ultimate bearing capacity showed an increasing trend,the growth rate decreased to some extent;as the stirrup spacing and eccentricity increased Stress performance is reduced.In terms of seismic performance,as the axial pressure ratio increases,the energy dissipation coefficient gradually decreases and the decrease is getting smaller and smaller,but the trend of decreasing stiffness decreases;as the thickness of the GFRP tube increases,the ultimate load of the specimen The force will increase,but the degree of increase will decrease;the deformation capacity will be greatly improved,the energy dissipation coefficient will be increased,and the stiffness will be degraded more slowly.The restraining effect when the axial compression ratio 0.50 is better than that of the specimen with the axial compression ratio 0.35.With the increase of the distance between the spiral stirrups,the ultimate bearing capacity of the specimen showed a downward trend and the decrease was reduced;the deformation capacity and energy dissipation coefficient of the specimen decreased;the stiffness deteriorated faster and the ductility coefficient was smaller The specimens with large pitches have poor seismic performance.As the axial pressure ratio increases,the influence of the pitch on the test piece increases.According to the simulation results,it provides a scientific basis for the follow-up scholars' research and the application of composite columns in actual engineering.