Numerical Analysis Of Compressive Performance Of Concrete Columns Strengthened With FRP-grid Reinforced ECC

Engineered Cementitious Composites(ECC)has excellent properties such as high toughness and good crack resistance.Fiber Reinforced Polymer(FRP)grid is of advantages including lightweight,high strength,convenience in construction,application in severe environments and so on.If a composite material,namely,FRPgrid reinforced ECC,which combines the advantages of the both two materials,is used to strengthen concrete columns,the strengthened concrete columns would capture much higher performance.However,the research on concrete columns strengthened with FRP-grid reinforced ECC is rarely seen in the literature.In this paper,the finite element analysis software ABAQUS was used to analyze the axial compressive performance of cylindrical concrete columns strengthened with FRP-grid reinforced ECC.This study would provid theoretical support for the application of the composite material in reinforcing concrete structures,which has important scientific significance and engineering application value.This paper mainly contains the following four parts.Firstly,the finite element analysis software ABAQUS was selected to establish the finite element model and do the calculation analysis for the specimens of compression tests on FRP strengthened concrete columns and RC columns strengthened with steel-mesh reinforced ECC and bending tests on FRP-grid reinforced ECC plates from the literatures.The simulation results was compared with the test results,the the suitable material constitutive model and finite element model consistented with the test results were selected,which laid the foundation for the following study of the paper.Secondly,taking ECC thickness,FRP-grid size and concrete strength as variable,axial compressive performance of cylindrical concrete columns strengthened with FRP-grid reinforced ECC specimens was analyzed by finite element simulation.The failure mode of the strengthened column was analyzed.The load-displacement,concrete strain,ECC tensile strain and FRP-grid strain curve were plotted.The results showed that with the constraint of composite material,the peak bearing capacity of the strengthened column was greatly improved and the corresponding peak displacement was enhanced slightly;in the decline stage after peak bearing capacity,a good deformation ability was observed.Thirdly,the influences of ECC thickness,FRP-grid size and concrete strength on the effectiveness of the reinforcement were analyzed.And the results showed that with the increase in ECC thickness,the peak bearing capacity of the strengthened column increased linearly.With the decrease in FRP-grid size,the deformation capacity in the descending section of the load-displacement curve increased obviously.The higher the strength of the concrete is,the higher the peak bearing capacity of the strengthened column is,and the faster the decay rate of the bearing capacity of the specimens is in the decline stage after peak bearing capacity.At last,the peak stress calculation model of cylindrical concrete columns strengthened with FRP-grid reinforced ECC was proposed considering the lateral constraint of ECC and FRP-grid composites on core concrete based on the finite element calculation results.The stress-strain model of cylindrical concrete strengthened with FRP-grid reinforced ECC was proposed using the widely-used concrete constitutive model proposed by Hogenestod,and the theoretical model was verified by the results of finite element simulation considering more changing in the ECC thickness,FRP-grid size and concrete strength.