Dynamic response of steel-reinforced concrete-filled circular steel tubular members under lateral impact loads

摘要

In this study, dynamic response of steel-reinforced concrete-filled circular steel tubular (SRCFST) members was experimentally studied under lateral impact loads. Eighteen SRCFST specimens were prepared and tested by the drop hammer impact test system. Various parameters, namely, cross-section of profiled steel, impact velocity and impact direction for I section profiled steel were considered to examine their influences on the failure mechanism, impact force, impact duration, displacement response and energy absorption. Since the beams may be of different constraints at boundary and the columns are axially loaded, boundary condition and axial load level were also considered. The experimental results show that the energy dissipation ratios (Eab/Ek) of all tested specimens except CIFP2-0 are more than 85% and the maximum energy dissipation ratio reaches 97.5%, indicating SRCFST members can absorb large amounts of input energy. Moreover, the inserted profiled steel can effectively enhance impact resistance while reduce energy absorption. It is also found that the peak value (Fmax) of impact force is very sensitive to the variation of impact velocity. The plateau value (Fplateau) of impact force and displacement response are very sensitive to the variation of boundary conditions and axial loads, which can significantly change the lateral flexural stiffness of specimens. Given the same impact energy input, SRCFST members with cruciform section profiled steel under fixed-fixed boundary conditions exhibit the best impact resistance performance with the lowest mid-span displacement.