Research On Mechanical Properties Of Concrete-Filled Stainless Steel Tube Stub Columns

With the development of ultra-high-rise and super-long-span structures,the strength and corrosion resistance of traditional concrete-filled steel tubular members are fall when they are used in modern building structures.In order to improve the durability,sustainability and load capacity of the components,the anti-corrosion stainless steel tube is used instead of the steel tube to form the concrete-filled stainless steel tube stub column(CFSST),so as to enhance the plasticity and durability of the components.In this paper,the properties of CFSST stub columns under axial compression are discussed,and their axial compression load capacity is predicted by BP neural network modeling method.The main work includes the following:(1)Axial compression experiments were carried out on 24 CFSST stub columns.The specimens’ failure modes were studied and the load-displacement curves of the specimens were discussed.The influence of steel tube thickness,the type of section and concrete strength of the CFSST stub columns was discussed under the axial compression.The results show that the concrete-filled circular stainless steel tube(CFCSST)stub columns bulges in the middle,and the surface of the stainless steel tube bulges in many places when the axis of the concrete-filled square stainless steel tube(CFSSST)stub columns.With the increase of steel tube thickness,the load capacity of CFSST stub columns under the axial compression is improved.And the load capacity and deformation performance of CFSST stub columns improve with the increase of concrete strength.(2)The stress state of core concrete and stainless steel tube is illustrated,and the mechanism of CFSST stub column under axial compress is analyze.Based on the experimental date,considering the constraint of stainless steel tube on core concrete,the calculation formulas of load capacity of CFCSST stub column and CFSSST stub column under axial compression are put forward.(3)The finite element model of the CFSST stub column was established by ABAQUS software..The mechanical characteristics of the CFCSST stub column and the CFSSST stub column in each stage were studied by comparing the experimental and simulation results.The load-displacement curve and ultimate load capacity of CFSST stub column are analyzed,and the stress and strain development of the CFSST stub column in each stage is discussed.(4)A total of 186 experimental data of CFSST stub columns under axial compression were collected.Using MATLAB software,taking the influencing factors of axial compression load capacity of members as input parameters,and the axial compressive load capacity of the specimen was used as the output parameter.The experimental data of CFCSST stub columns and CFSSST stub columns were used for training and testing,and their single hidden layer BP neural network models were established.The predicted values are compared with the calculated values of the three load capacity calculation models.The results show that the BP neural network model established in this paper has the highest simulation accuracy and can be used as an effective method to predict the axial compression load capacity of CFSST stub columns.