Study On Axial Compression Performance Of Geopolymer Concrete-filled Double-skin Steel Tubular Stub Columns

The survival process of ordinary Portland cement will generate a large amount of CO₂emissions into the air,which will cause a great burden on the environment.Geopolymer concrete is made of industrial waste-fly ash,slag and alkali activator,which is a green environmental friendly materials and can partially or completely replace ordinary concrete.The geopolymer concrete-filled double-skin steel tubular is composed of two concentrically placed steel tubes and sandwich geopolymer concrete,which is a new type of green structural form.At present,some scholars have done some research on the application of geopolymer concrete in composite structures,but the research is not complete.Therefore,the paper studies on axial compression performance of geopolymer concrete-filled double-skin steel tubular stub columns,and combined with the finite element simulation,makes a deep research on its failure mode,axial load-strain relationship and parameter influence.The research work in this paper includes:?1?A total of 48 concrete-filled double-skin tubular stub columns were tested,including24 outer and inner circular concrete-filled double-skin tubular stub columns and 24 outer squarer and inner circular concrete-filled double-skin tubular stub columns.The circular and square test specimens each have 12 sandwich concrete specimens as geopolymer concrete specimens,and 12 sandwich concrete specimens as ordinary concrete specimens.The parameter comsiderd in the test are:cross-sectional form,concrete type,compressive strength of aconcrete cylinders,size ratio of inner and outer steel pipes,and outer diameter?width?thickness ratio.The failure mode,axial load-stain curves,ultimate bearing capacity,compressive stiffness,peak strain,and ductility of the geopolymer concrete-filled double-skin steel tubular stub columns under axial compression were obtained.?2?ABAQUS is used to simulate the axial compression of geopolymer concrete-filled double-skin steel tubular stub columns.The results of the finite element simulations are in good agreement with the experimental curves.It si verified that the constitutive relationship model of the selected steel and concrete is not only suitable for the ordinary concrete-filled double-skin steel tubular stub columns,but also suitable for the geoplymer concrete-filled double-skin steel tubular stub columns.?3?Based on the verified finite element model,the parameters are analyzed through 403examples.The parameters were as follows:yield strength of the outer steel tube,yield strength of the inner steel tube,compressive strength of the sandwich concrete cylinder,size ratio of the inner and outer tube,diameter?width?ratio of the outer steel tubes,and thickness ratio of inner steel tubes.On the basis of parameter analysis,a simplified calculation method of ultimate bearing capacity,axial compression stiffness and peak strain of the?geoplymer?concrete filled double-skin steel tubular stub columns were proposed.