Research On The Mechanical Properties Of GFRP-Concrete-Steel Double Skin Tubular Columns Under Eccentric Compression

GFRP-concrete-steel double skin tubular columns is a new type of composite components,it consists of three parts: the outer GFRP tube,the inner steel tube and the concrete between them,it has all the advantages of double GFRP tube concrete composite column,double steel tube concrete composite column and GFRP tube core concrete column.GFRP tube can improve the bearing capacity of the composite components by restricting the core concrete.At the same time,GFRP tube can effectively protect concrete and steel tube.The composite column has good ductility and seismic performance.It can be seen that the combined structure has broad application prospects.Some achievements have been made in the research on the mechanical properties of GFRP-concrete-steel double skin tubular columns under eccentric compression,however,the study of eccentric compression is relatively scarce.Considering the actual situation,most of the columns are eccentrically compressed under working condition.Therefore,it is significant to study the mechanical properties of this structure under eccentric compression.In order to study the mechanical properties of GFRP-concrete-steel double skin tubular columns under eccentric compression,this paper will build up the finite element model of GFRP-concrete-steel double skin tubular columns.On the basis of verifying the correctness of the model,simulate large number of components,study in depth the influence of four kinds of parameters,such as hollow ratio,length to diameter ratio,concrete strength and eccentricity on the mechanical properties of the composite components.Main research work includes:1.Through the finite element software ANSYS,combined with the test component parameters,establish the finite element model of the corresponding GFRP-concrete-steel double skin tubular columns.By comparing the ultimate bearing capacity and loaddisplacement curve to verify the correctness of the constitutive relation and the modeling method.2.On the basis of verifying the correctness of the model,design the cross-section forms of GFRP-concrete-steel double skin tubular columns,extended parameter,determine the parameters of the working conditions to be studied,establish the finite element model,obtain equivalent stress nephogram,the ultimate bearing capacity and load-displacement curve ofGFRP-concrete-steel double skin tubular columns by controlling hollow ratio,length to diameter ratio,concrete strength and eccentricity.3.Compared with the above four kinds of different influence factors,According to the failure mode which is reflected by the equivalent stress nephogram,load displacement curve and the ultimate bearing capacity analysis similarities and differences and change rule,determine the influence rule of the mechanical properties of GFRP-concrete-steel double skin tubular columns under eccentric compression above four influence factors.4.Analysis results show that with the increase of length to diameter ratio and eccentricity,the bearing capacity of composite columns decreases sharply,and the ultimate displacement increases,composite columns have a good ductility.Reducing the hollow ratio and increasing the steel ratio can improve the bearing capacity and ductility of the composite columns,and the steel ratio has obvious influence on the ductility.The change of concrete strength has the most significant influence on the bearing capacity of composite columns,but the strength of concrete increases,the ductility is poor.When the hollow ratio is small and the strength of concrete is low,the confinement effect of GFRP outer tube is obvious,and the bearing capacity of composite columns is raised greatly and ductility is improved.