Study On Axial Compression Behavior Of FRP Confined Geoploymer Concrete

Geopolymer concrete is an energy-saving and environmentally friendly material.However,the geopolymer concrete is brittle fracture under uniaxial stress state,and the deformation behavior under complex stress state needs further study.Therefore,this paper studies the effects of fiber-reinforced composites(FRP)layers and matrix strength on the axial compressive properties of FRP confined geopolymer concrete.The specific research content and details are as follows:1.The bearing capacity and ductility of FRP confined geopolymer concrete columns are greatly improved compared with unconfined geopolymer concrete columns.The axial stress-axial strain curves of FRP confined columns are approximately bilinear.Under the same matrix strength,the elastic section of the FRP-free confined column and the FRP confined column basically coincide.When the axial stress approaches the unconfined peak stress,the softening section after the peak stress of the FRP-free column evolves into the strengthening section of the FRP confined column.2.The axial stress-hoop strain curve of the FRP confined geopolymer concrete column can be divided into three sections,corresponding to the unconfined section,the transition section and the strengthening section dominated by the FRP constraint.According to the segmentation curve of the FRP confined column,it is found that as the strength of the matrix increases,the smaller the lateral deformation,the faster the FRP acts,and the smaller the transition radius.In addition,the initial stage FRP confined column is similar to the Poisson’s ratio of the unconfined column,and remains substantially at around 0.2.3.According to test data,the three-way compression formula of FRP confined geopolymer concrete column is obtained.It is found that the strength growth coefficient and the strain growth coefficient are smaller than the FRP confined ordinary concrete column.This law indicates that the geopolymer concrete is more brittle than ordinary concrete.4.Comparing the test curves of the stress-strain with the calculation curves of the analytical model formulas of Popovics and Jiang and Teng,it can be found that the strengthening section of the axial stress-axial strain curve exists the certain deviation,the model is closer to the test curve after the parameters are modified.5.The calculation curve of FRP confined geopolymer concrete were obtained by using ABAQUS.It is found that the calculated value of the axial strain is too small,the calculated curve of the elastic section agrees with the test curve,and the relative errors of the axial stress and the axial strain are less than 15%.