Experimental study of RC columns and composite columns under low-velocity impact

摘要

In this study, thirty specimens were tested using a drop hammer impact test machine, comprising six reinforced concrete columns and twenty-four specimens of the composite columns. The composite columns include steel tubular-encased reinforced concrete (R-ST) columns, steel-reinforced concrete-filled steel tubular (S-ST) columns, hollow concrete-filled double steel tubular (H-DS) columns, and solid concrete-filled double steel tubular (S-DS) columns. The influences of different axial load levels and different column sections on the responses, such as impact force, the impact duration, the deflection, and the longitudinal strain, are investigated and discussed in detail. The results indicate that compared with the brittle failure of RC columns, all R-ST columns and composite columns behaved in a ductile manner. Moreover, the steel tube can effectively enhance the impact resistance of RC columns. The variation of axial load level has an important influence on the axial load attenuation, deflection, the impact duration, and the plateau value of the impact force. Under the same test conditions, S-DS columns have the best impact resistance with the lowest mid-span displacement, followed by H-DS columns, whereas the impact resistance of S-ST columns is slightly inferior with the highest mid-span displacement among the composite columns.