Finite Element Analysis On Mechanical Property Of Concrete Filled Circular Steel Tube Composite Columns With Inner GFRP Tube

Compared with ordinary reinforced concrete columns,steel reinforced concrete columns,concrete filled steel tube columns,GFRP confined concrete columns,GFRP-concrete-steel double-skin tubular columns and double steel tubes concrete columns,concrete filled steel tube has a light-weight and high strength,high temperature resistance,corrosion resistance good plasticity as well as good seismic performance.A new type of composite column formed by GFRP tube with many advantages improves the mechanical properties.The mechanical properties of composite columns under axial compression and uniaxial eccentric loading are analyzed by ABAQUS software.The main content and conclusions are as follows:?1?The influence parameters are determined such as the thickness of inner circular GFRP tube?t₂?,the winding angle of GFRP tube,the diameter of GFRP tube,the thickness of outer steel tube?t₁?,the internal and external concrete strength grade and aspect ratio???.Through the load?kN?-longitudinal displacement?mm?curve of axial loading columns,the variation law of bearing capacity and ductility are obtained.The results show that the thickness of inner circular GFRP tube and outer steel tube have great influence on the bearing capacity and ductility of this composite columns.When the strength grades of core concrete and annular concrete are different,only to improve the strength grade of annular concrete is more obvious than to enhance the strength grade of core concrete for the growth trend of the bearing capacity of this component.The influence of aspect ratio on the bearing capacity of composite columns is small,but it has great influence on ductility.Compared with other influence parameters,the winding angle of GFRP tube has the least effect on the bearing capacity and ductility of composite columns.?2?The finite element method is used to analyze the uniaxial eccentric loading columns.The simulation results show that the composite columns have higher bearing capacity and better ductility than the ordinary concrete filled steel tube columns.The ultimate bearing capacity and ductility drop with the increase of the eccentricity and the ratio of length to diameter,and go up with the increase of the thickness of inner GFRP tube and outer steel tube.?3?According to the previous formula,the calculation formula of ultimate bearing capacity of axlal loading columns is obtained.The results are compared with the outcomes of finite element simulation and the literature test.The influence of four parameters are considered,including the thickness of inner GFRP tube?t₂?and outer steel tube?t₁?,the eccentricity?e?and aspect ratio???.The formula for calculating the ultimate bearing capacity of uniaxial eccentric loading is fitted.The results are compared with the finite element results,showing fitting preferably.