Dynamic Response Of CFST Columns Under Explosive Load

In recent years, the detonation terrorism internationally was in flood, already becomes serious threaten to the international society and the people's life and property. For important buildings and safeguard structure, the functions of blast or impact loads are usually needed to consider. Therefore the research of the dynamic response of engineering structure under explosive load is an important topic. Concrete filled steel tube(CFST) columns have high bearing capacity, good plasticity and toughness and the convenience for manufacture and construction, have been applied widely in engineering structure. At present there are many researches on CFST component's mechanical properties under quasi-static load. However, there are few investigations considering accidental load function such as explosion, impact or penetration. Consequently, the research on CFST columns'dynamic response under implosive load has important significance. The paper adopts theoretical analysis and numerical simulation to study dynamic response of square CFST column under surface burst explosion load.Firstly the square CFST column is simplified as the equivalent single degree-of-freedom system by making use of CFST unified theory and the ideal rigid-plastic material model is used. The maximum dynamic displacement formula is deduced using the method that analyses the single degree-of-freedom. Then the column's maximum dynamic displacement under different scaled distance is calculated by using the theoretical formula and the finite element software, and the results have been carried calibrated.In view of column's practical work situation, the component's dynamic response under surface burst explosion load has further carried on numerical analysis. The result indicates: along with the scaled distance increases, the whole distortion of the column reduces gradually, the damage of inside concrete and steel pipe outside reduce gradually. Under the function of surface burst explosion load, when the scaled distance is small, damages of the inside concrete are serious, but steel pipe can absorb majority of energy because of own large rigidity, high intensity and good ductility. Moreover while concrete damages it expands all around, which may limit the steel pipe to have buckling, therefore the middle part of back surface and the both ends of front surface of steel tube have damaged only in a small part of the region. So the column doesn't have instantaneous collapsing when receives high-pressured or instantaneous load. Therefore CFST column has important application value in the protective structure. It indicates that the explosion load has little influences on the square CFST column based on the analysis of the displacement and erosion of the material at different scaled distance.