Expeirmental Study And Numerical Simulations On Seismic Behavior Of PVC-FRP Confined Reinforced Concrete Column

PVC-FRP confined reinforced concrete column is a new type of compositecomponent, which is formed by putting the reinforcement and pouring concrete in thePVC-FRP tube. PVC-FRP confined concrete column have many advantages such ashigh bearing capacity, convenient construction, superior durability and good ductility.The experimental study and numerical simulations on seismic behavior of PVC-FRPconfined concrete column is developed with the different axial compression ratios andthe hoop spacing of CFRP strips.According to the experimental study of seismic behavior about eight PVC-FRPconfined concrete columns under low frequency cyclic load, the effects of axialcompression ratios and the hoop spacing of CFRP strips on the seismic behavior ofPVC-FRP confined concrete column about the looping curves, the rigidity degradation,the energy dissipation capacity, the horizontal bearing capacity and the ductility areanalyzed, the results show that the vertical cracks of PVC tube at the bottom of thespecimens which are wrapped by the hoop spacing of twenty millimetre of CFRP stripsand CFRP are appearing under the axial compression ratio zero point four, theperformance of failure morphology of other specimens is that the longitudinalreinforcement yield, the concrete is crushed, the longitudinal reinforcement and PVCtube is experiencing larger deformation, the bending extent of specimens is increasingcontinuously, test results are flexural failure; The load-displacement looping curves ofspecimens maintain good stability and plumpness, and specimens have better energydissipation capacity and seismic behavior. With the increase of axial compression ratio,the initial stiffness and the energy dissipation capacity are enhanced, the horizontalbearing capacity is increased correspondingly but the attenuation of capacity isaccelerated, ductility is decreased; With the decrease of hoop spacing of CFRP strips,the initial stiffness and the horizontal bearing capacity incrase greatly, but thedisplacement ductility is decreased. the effects of the change of hoop spacing of CFRPstrips on the rigidity degradation and the energy dissipation capacity of specimens withlarger axial compression ratios are obvious.Based on the experimental study, the stress-strain relation of PVC-FRP confinedconcrete is used, the section of PVC-FRP confined reinforced concrete column isanalyzed under low frequency cyclic load, the effects of axial compression ratio andhoop spacing of CFRP strips are considered, using the limit equilibrium condition offorce on the section of the specimen, the formula of flexural capacity of PVC-FRPconfined reinforced concrete column is derived under low frequency cyclic load, the seismic design procedure of PVC-FRP confined concrete column is put forward.A nonlinear calculation program is developed to make full-process analysis onPVC-FRP confined reinforced concrete column by using fiber model method based onthe stress-strain relation of PVC-FRP confined concrete, the calculation skeleton curvesof PVC-FRP confined reinforced concrete column are obtained, the calculation ofskeleton curves is verified. On this basis, the calculation method of the skeleton curvesis simplified, the loading and unloading rules of PVC-FRP confined reinforced concretecolumn is provided, the restoring force model of PVC-FRP confined reinforced concretecolumn is established.Using finite element analysis software ABAQUS, the constitutive relations ofmaterials are chosen reasonably, the finite element analysis model of PVC-FRPconfined reinforced concrete column is established, the analysis model is verified. Onthis basis, further studies are carried out, the effects of concrete strength, longitudinalreinforcement ratio, layer of CFRP strips and shear span ratio on the skeleton curves andthe rigidity degradation are discussed, The mechanical behavior of PVC-FRP confinedreinforced concrete column is analyzed under low frequency cyclic load, and theworking mechanism of PVC-FRP confined reinforced concrete column is revealedunder low frequency cyclic load.