CALCULATION METHOD FOR IMPACT RESISTANCE OF CIRCULAR CONCRETE-FILLED DOUBLE-SKIN TUBULAR COLUMNS WITH EXTERNAL STAINLESS STEEL TUBE

Reinforced concrete and concrete-filled steel tubular members have been widely used in engineering structures and the design methods for the impact resistance have been suggested. However, studies on the impact resistance of circular concrete-filled double-skin tubular (CFDST) columns with external stainless steel tubes are limited. In light of this, the finite element analysis (FEA) model considering the coupling effect of axial and impact loads was established by ABAQUS based on preliminary experimental research. The impact mechanism under the combined action of axial and impact loads was investigated. The effects of axial load ratio, nominal steel ratio and other parameters on the impact resistance were studied. The formula used to predict the dynamic increase factor (DIF) of the plateau impact force subjected to axial and impact loads was suggested. The results show that the plastic deformation of outer steel tube is the main energy dissipation mechanism of members. Axial load ratio has a negative effect on the impact resistance of members, and the effect is significant when the axial load ratio exceeds 0.5. Nominal steel ratio, strengths of outer tube and concrete, impact velocity and cross-sectional diameter have significant effects on the impact resistance of members. The formula suggested in this study can reasonably predict the plateau impact force of members under lateral impact.