Study On Axial Compression Behavior Of Partially Encased Steel Concrete Columns

Partially encased steel concrete columns,referred to as PEC column,is the union product of steel and concrete,which is a new type of structure based on the modern steel structure and concrete structure developed.In this paper,the mechanical performance of PEC composite columns structure under axial load is studied by the combination of structural tests,numerical simulation and theoretical calculation.In this paper,the static test of two PEC composite columns under axial load is carried out.The stress of the specimens during the test is observed and the characteristics of the specimen are analyzed,and the working principle and combination are studied.The failure mode of the composite structure under axial load is analyzed,and the mechanical properties of the composite structure are analyzed from the aspects of bearing capacity,load deformation and ductility.A number of PEC composite column structure models were established by finite element analysis software,and the numerical simulation analysis of the mechanical behavior of the structure model is carried out.The simulation results and the experimental results were compared to verify the validity and reliability of the finite element simulation software results.Based on this,the effects of steel high thickness ratio,concrete strength,spacing of bars and steel ratio on the initial stiffness,ultimate bearing capacity and ductility,and analyzed the stress performance of such composite structure.Finally,based on the current specifications,the ultimate bearing capacity of PEC composite columns is calculated by the simple superposition principle,and compared with the results of numerical simulation and tests.The research results show that the PEC composite columns have good mechanical performance,and the results of theoretical calculation and numerical simulation are in good agreement with the experimental results.With the ratio of steel height to thickness increases,the deformation capacity of the specimens increases,but the initial stiffness and the ultimate bearing capacity of the specimens decreases.With the increase of steel ratio,the ultimate bearing capacity of specimens is improved.With the increase of steel tie bar spacing,initial stiffness of specimens is constant,ultimate bearing capacity and ductility decreased with the increase of load.When the specimens reached the yield load,strength degradation accelerated,and the ductility of small steel tie bar spacing specimen performance is better.Within the scope of this research,concrete strength change is not significant on the stress performance.The results of this study provide a reasonable theoretical basis and reference for the future design of PEC column,and have certain academic and engineering application value.