Experimental Study And Theoretical Analysis On Mechanical Behavior Of PVC-FRP Confined Concrete Column

The developing direction of modern structural engineering is large, complex and innovative, and the demand of technical content is increased, which proposed the urgent need for the innovation of structural system.To overcome the drawbacks and shortcomings such as strength, deformation, stiffness and durability of existing structure, the new type PVC-FRP confined concrete column is systemically studied.Based on the static equilibrium condition and the yield criteria of components, the effect of the modified confinement ratio, the lateral confinement ratio, unconfined concrete strength and the properties of confining material on bearing capacity of confined concrete column were carefully considered, the unified bearing capacity model of confined concrete column is established, it may be applicable to calculation of the bearing capacity of steel-confined concrete, concrete filled steel tube and FRP-confined concrete. To further consider the effect of shape coefficient of concrete section, the gravity ratio X of FRP to FRP tube, and the reduced coefficient of confinement effect k_r on the ultimate compressive strength of FRP-confined concrete column, then the unified strength model of FRP-confined concrete column is established. The predictions of the models agree well with test data.The experimental study of PVC-FRP confined concrete column subjected to axial load is presented, the effect of the spacing of FRP straps, axial reinforcement and slenderness ratio on the failure mode, bearing capacity, deformation and stress-strain relationship of PVC-FRP confined concrete column are analyzed. It is proved that PVC-FRP confined concrete column has many advantages by coMParing the behavior of PVC-FRP confined concrete column with that of existing structure. Based on the experimental study, considering the effect of the spacing of FRP straps, axial reinforcement and slenderness ratio, the calculating formula of bearing capacity and ultimate compressive strain for PVC-FRP confined concrete column is proposed, and the stress-strain model of PVC-FRP confined concrete column is established. The predictions of the model are well in accordance with test data. The experimental study on bearing capacity of PVC-FRP confined concrete short column subjected to eccentric load, the effect of the spacing of FRP straps and eccentricity on the failure characteristic, ductility, bearing capacity, bending moment-curvature relationship and load-deflection relationship of PVC-FRP confined concrete short column are analyzed, and the plain section assumption of concrete column is verified. Based on the experimental data, the increscent coefficient of eccentricity is introduced, and then the formula of the bearing capacity of PVC-FRP confined concrete short column under eccentric compression is put forward. Based on the plain section assumption and the proposed stress-strain model of PVC-FRP confined concrete column, the formula of limit values of axial compression ratio is deduced, and then the bending moment-curvature model and load-deflection model are established. The predictions of the models agree well with test data.Experimental study on durability of CFRP and PVC-FRP confined concrete column in the alkaline liquor and chloride liquor is also presented. The effect of different environment on the mechanical behavior of CFRP and PVC-FRP confined concrete column is analyzed, which includes the bearing capacity, deformation and stress-strain relationship of experimental member, it is shown that the PVC-FRP confined concrete column has good durability.