| Steel tube-reinforced concrete column comprising core concrete-filled steel tubular and pipe outside reinforced concrete has a good mechanical performance.Stage construction of the composite column,due to the composite secondary stress,can make the early construction of the core concrete-filled steel tubular part bear the greater part of the total axial force,the advantages of high axial bearing capacity of concrete-filled steel tube column to be fully used,the latter construction of the outside reinforced concrete part mainly bear bending moment produced by the horizontal loads such as wind and earthquake.Compared with common reinforced concrete column,steel tube-reinforced concrete column has better compression and seismic performance.While some relevant provision to design composite column which mostly are following the rules of the ordinary reinforced concrete column.so deep understanding the mechanical properties of steel tube-reinforced concrete column,it is great significance for safety and reasonable seismic design of the composite column.This paper mainly researches on the following several aspects:(1)The finite element models of steel tube-reinforced concrete columns are established by nonlinear finite element software ABAQUS.On the basis,analyzing the influence of some parameters on the displacement ductility coefficient of steel tube-reinforced concrete column.The formula of displacement ductility coefficient of-composite column which reflects the influence of key parameters by fitting of finite element data is proposed,(2)By section analysis to study the behavior of steel tube-reinforced concrete columns,on the basis of it using the strip method accounting for the secondary stress to analyse the effect of axial force redistribution and compression depth,the limited values of nominal axial compression ratio and minimum stirrup characteristic values under ductility demand(u△≥3)is also suggested which can provide a reference for designing steel tube-reinforced concrete column.(3)the detection of performance analysis is based on MATLAB,the performance limit states equation is established according to the plastic hinge model,providing a reference for seismic design based on the performance of the composite column. |
