Research On Finite Element Analysis And Practical Design Method Of Concrete-filled Stainless Steel Tube Under Compression Bending

Concrete filled stainless steel tube(CFSST)is a new type of composite structure,which not only has the advantages of concrete-filled steel tube(CFST),but also has the advantage of stainless steel corrosion resistance.Therefore,the offshore platform,sea bridge and other building structures have broad prospects.In view of the fact that there is only concrete filled steel tube design codes but no concrete filled stainless steel tube code at present,in order to make the CFSST serve the engineering construction better,the design method of CFSST under compression bending is studied.It has important engineering significance.Based on the previous experimental study of CFSST,this paper studies the mechanical properties of CFSST under axial pressure,pure bending and bias.The main works can be summarized as follows:1.The experimental data of CFSST members(including 180 circular section members and 240 square rectangular section members)under axial compression,pure bending and compression bending were collected and summarized.Four kinds of existing CFST design codes,including the AISC(2010),EC4(2004)standard,local standard in fujian province(DBJ/T13-51-2010)and China national standard(GB 50936-2014)are calculated and analyzed.The applicability of the existing CFST design codes for the calculation of concrete-filled stainless steel tube members is also explored.2.On the basis of reasonably selecting the stress-strain relation model of stainless steel and core concrete,considering the nonlinearity of material and geometry,and the interaction between stainless steel and core concrete,the axial compression of concrete-filled stainless steel tube is established.The finite element model of axial compression,pure bending and compression bending member is compared with the experimental results to verify the accuracy of the established finite element model.3.The finite element model is used to analyze the working mechanism of CFSST members under axial compression,pure bending and compression bending.And the difference of mechanical properties between CFSST members and CFST members is also compared.In particular,the difference in the role of constraints.4.The nonlinear finite element model is used to analyze the parameters of the system,and the influence factors on the behavior of concrete filled stainless steel tube under axial compression,pure bending and compression and bending are analyzed,and the load-displacement curves are analyzed in detail.5.On the basis of parameter analysis,the practical formulas for calculating the axial compressive strength,the axial compression stability,the bending bearing capacity and the compression-bending equation of the CFSST are regressed.Compared with the experimental results,the formula presented in this paper is more consistent with the test results than that of the existing CFST code,which can provide a basis for the relevant departments to formulate the design code for CFSST.