Investigation on the lateral impact responses of circular concrete-filled double-tube (CFDT) members

To meet specific design requirements or achieve superior structural performances, a new type of concrete-filled steel tubular (CFST) composite structure called as concrete-filled double-tube (CFDT) was proposed in recent years. Despite intensive studies on structural performances of CFDT members under various loading conditions, very limited investigations on impact responses of CFDT members can be found in literature. During the service life structural members may be subjected to extreme loads such as impact load, therefore the investigation on impact responses of CFDT members is essential for impact resistant design and assessment. This paper presents experimental study and finite element analysis (FEA) results of lateral impact responses of circular CFDT members. A total of twelve circular CFDT specimens with various parameters are tested by utilizing a drop hammer impact system. The damage modes, impact forces, displacement responses and energy absorption capacities of CFDT members from the impact tests are evaluated and compared, followed by numerical simulations using explicit software ABAQUS. With the verified numerical models, the damage evolution of each component and its contribution to impact loading resistance are extracted and analysed. In addition, the performances of CFDT and common CFST members under impact loading are compared.