Experimental Research On Bearing Capacity Of Concrete-filled Double Steel Tubular Structure

Along with the rapid development of our country construction,more than tenyears,concrete-filled steel tube because of its unique advantages is widely used in singleand multi-layer industrial workshop, all kinds of support, high-rise building and bridgestructure.Although many domestic scholars have researched mechanical performanceand bearing capacity of concrete-filled steel tube structure,at the same time alsoobtained a series of achievements, but the study of improve of bearing capacity of theexisting CFST structure is less, Along with reinforcement design needs of bridgestructure of concrete-filled steel tube,so it is necessary to research bearing capacity ofconcrete-filled double steel tube,which is formed by outsourcing CFST. Through thefinite element method and reinforcement model test research of concrete-filled steeltube, in this article the following results are obtained:①On the basis of ultimate bearing capacity research of axial compression shortcolumns of concrete-filled double steel tube,put forward the formula of the ultimatebearing capacity of axial compression short column of concrete-filled double steel tubeof inner CFST with initial stress;②In this article through reinforcement model test of concrete-filled steel tube, thefollowing results are obtained:1) reinforced Component of CFST have good ductility,through the elastic, elastic-plastic and failure stage, also have obvious yield stage;2)damage form of specimen belong to drum type failure;3)theN N、N hrelationcurves of inner steel pipe have consistent trend with law of outer steel pipe, the yieldingload of inner, outer steel tube is basically the same, inside, outer steel tube arrive at theyield condition before specimen damage, axial deformation and circumferentialdeformation of the outer steel tube were greater than the inner tube, until the specimenbreaks, bearing capacity of specimen arrive to ultimate value along with local bucklingof middle section of the outer pipe;③The application of finite element software ANSYS arrived the results ofreinforced short columns of CFST, though there is certain difference With the measureddata values, but destructive rule of specimen consistently trend with load-strainrelationship curves, so the finite element analysis software can correctly calculate thebearing capacity of reinforced short column of concrete-filled steel tube;④The experimental results and calculated value of formula are contrasted, which indicate that this formula used to calculate the bearing capacity of reinforced shortcolumns of concrete-filled steel tube is feasible;⑤Use of ANSYS software, analysis influence of ultimate bearing capacity ofreinforced short column of concrete-filled steel tube through change initial stress valueof inner CFST、poisson’s ratio of concrete、 the strength of outer steel pipe、thicknessof outer steel pipe（ratio of the steel)、strength grade of outer concrete. the followingachievements are obtained:1) the bearing capacity of concrete-filled double steel tube ofinternal CFST with initial stress will decrease with initial stress value increase, whilethe deformation will increase with initial stress value increase;2)the effect of differentpoisson’s ratio of concrete on bearing capacity of the specimen is very little, so it isfeasible for finite element method with concrete poisson’s ratio0.2of elastic stage;3)with increase of the steel pipe strength, the steel pipe wall thickness and the strengthlevels of outer concrete, ultimate bearing capacity of axial pressure short column ofconcrete-filled double steel tube will also increase,but if change the steel pipe strength,itwill cause the greatest impact of specimen bearing capacity;...