Hysteretic Model Study On The Four-tube Concrete Filled Steel Tubular Lattice Column

The concrete filled steel tubular (CFST) lattice column is connected by the steel tube concrete column and the lattice members such as the steel pipe, the steel plate and the section steel. Compared with ordinary reinforced concrete columns, the CFST lattice column has many advantages such as high bearing capacity, good ductility, quick and convenient construction, It can give full play to the advantages of each material and so on, So it is widely used in the huge structure, industrial plants, bridges and high-rise buildings and other practical projects. At home and abroad, the research on the CFST lattice column is relatively few, and it is focused on the axial compression and eccentric compression performance of the component. In view of the present situation, more and more scholars have conducted experiments on the seismic behavior of the steel tubular column in recent years, but the analysis of the parameters and the theoretical research of the component are very limited, So it has very important practical significance to study the CFST lattice column.Based on the previous four tube CFST lattice column pseudo-static test, the finite element ANSYS software was used to simulate the 3D nonlinear numerical analysis of the four tube CFST lattice column, and the influence of axial compression ratio, equivalent slenderness ratio and material ratio on the hysteretic behavior of members were focus on research. Through the analysis of the above parameters and the related theory, the calculation formula of the restoring force model of the CFST lattice column was proposed, and the applicability and precision of the restoring force model of the CFST lattice columns with different node types and different loading modes were studied.Research results show that:The calculation results of finite element simulation of the CFST lattice column under low cyclic loading test are in good agreement with the experimental results. The optimum range of axial pressure ratio, equivalent slenderness ratio and the material ratio were proposed by using the finite element analysis method. Based on the parameter analysis, the restoring force model of the CFST lattice column is proposed. This model can be applied to the "N" node and the "K" type joints of steel tubular column, and the different loading methods (displacement control loading, load-displacement control loading) on the results of the calculation of the model is very small that can be neglected.