Study On Behavior Of Rectangular Concrete-filled Stainless Steel Stub Column Under Axial Loading

In order to study the axial compression bearing capacity of rectangular stainless steel tube concrete stub columns,7 groups of rectangular stainless steel concrete(CFSST)stub columns with different cross-sectional dimensions were subjected to axial compression tests,and the failure modes,load-displacement curves,load-longitudinal strain curve,load-aspect ratio curve and load-transverse strain curves of different specimens were obtained,analyze the influence of rectangular section aspect ratio on the bearing capacity of specimens.Furthermore,the influence of the aspect ratio of the rectangular section on the bearing capacity of the specimen is analyzed.The results show that the typical damage pattern of rectangular CFSST short column under axial pressure is localized outward bending damage of the specimen.At the same aspect ratio,when the wall thickness of the specimen increases from 4 mm to 6 mm,the bearing capacity of the specimen increases by 25%-57%,but the displacement becomes smaller when the ultimate load is reached;At the same wall thickness,when the aspect ratio of the specimen increases from 1 to 2,the load-bearing capacity of the specimen decreases by 22%-30%.At the same time,the test data of this paper are compared with the calculation results of relevant codes and standards at home and abroad,the axial load-bearing capacity of CFSST stub columns is more than 14% higher than that of common carbon steel concrete-filled steel tubular stub columns of the same type.Based on the test results of this paper and the axial compression test data of rectangular CFSST short columns in the existing literature,through numerical fitting and theoretical analysis,the axial compression bearing capacity prediction formula of the specimens is obtained,and the calculation results of the relevant codes and standards of ordinary carbon steel tube concrete columns in different countries are compared and analyzed.The formula obtained in this paper is more suitable for the calculation of axial compression bearing capacity of concrete-filled rectangular CSFFT stub columns.This paper uses ABAQUS finite element software to establish a precise finite element model for the test components of this paper,selects the tested steel,concrete constitutive model,and replaces the finite element structure model for detailed meshing,and then sets the concrete and concrete that meet the test.Stainless steel tube interaction,boundary conditions and loading mode.Thus,the simulation analysis obtained the displacement-displacement curve and failure mode of each specimen,and compared the results of the finite element analysis and the test results of the axial compression performance of the rectangular CFSST short column.Then through ABAQUS finite element analysis,the rectangular CFSST short column under different parameters(tube wall thickness,concrete strength)was studied,and the results showed that:the different concrete strength members have almost the same trend in each stage of the curve.In the elasto-plastic stage,the concrete strength is the highest,the curvature of the elasto-plastic stage is the smallest,and the alternate displacement and displacement are transformed.With different parameter rectangular CFSST short column models,their ultimate bearing capacity finite element results are in good agreement with the formula calculation results,which proves once again The accuracy of the prediction formula is improved.