Study On Mechanical Behavior Of Concrete-Filled Square Steel Short Column With Inner CFRP I-shaped Profiles Under Eccentric Compression

With the rapid development of economy in recent years,the demand for the development of building structure is higher and higher,the demand for high-rise,long span and heavy load is also developing trend.As a new material,FRP material has been widely used in our daily life,however,the research and application of the compressive properties of FRP materials are less in structural engineering.This paper summarizes the research and application of the CFST structure and other types of components,on the basis of the previous research results,a test is carried out on the short column of CFST with inner CFRP I-shaped profile.In this paper,the eccentric compression tests of 7 groups with CFRP I-shaped profile and 2 common CFST short columns are carried out,and the effects of eccentricity,steel strength and steel ratio on the mechanical properties and ductility of the components are analyzed.The distribution and change of stress and strain of whole specimen and each part in each stage are analyzed.The mechanical properties of the common and typ:ical CFST specimen are compared and analyzed.Draw a conclusion,owe to the CFRP I-shaped profile,the ultimate bearing capacity will maintain a relatively stable.When the specimen yielded,the strain was about 30 percent of the strain when it was damaged and this proportion is affected only by the eccentricity.With the increase of eccentricity,the yield load and the rigidity are slightly reduced,and the decrease of ultimate bearing capacity is obvious,and eccentricity and bearing capacity are inverse proportion.Steel strength and steel ratio only affect the yield strength and ultimate bearing capacity and no effect on rigidity.CFRP profile can improve the ductility of the component very well.Finite element software ABAQUS is used to simulate 14 short columns with inner I-shaped CFRP profile and one common short column under eccentric compression,a supplementary analysis of the parameter variables,eccentricity,steel strength,steel ratio and concrete strength,that are not involved in the experiment.Draw a conclusion,the mechanical performance of the component in the finite element simulation is the same as that of the test.The load proportion of each part of the component is not affected by the eccentricity at the elastic stage.After the yield of the component,the proportion of the steel tube began to decrease gradually.With the increase of concrete strength and steel ratio,the ultimate bearing capacity of the component has been improved to a certain extent.Based on the limit equilibrium theory,unified theory of CFST and technical code for concrete filled steel tubular structrues of china,three kinds of calculation methods of ultimate bearing capacity is given.The results of calculation and analysis show that the three methods can accurately calculate the ultimate bearing capacity of a biasing short column,and the calculation method given by the standard is lower than the other two methods.