Analytical investigations on dynamic responses of SRCFST members under lateral impact loads

Very limited studies have been conducted to investigate the influences of different internal configurations and the size effect on the impact responses of SRCFST members. In this study, numerical simulations are conducted by using ABAQUS. The numerical model of SRCFST members under lateral impact directly incorporates material damage, strain rate effect and steel fracture, and the model is verified against available impact testing data. Following model verification, the impact behaviors of SRCFST members with four commonly used internal configurations of steel sections are compared and discussed. It is found that the damage modes of SRCFST members are largely unaffected by internal configurations. These internal configurations minimally affect energy absorption capacity, with a maximum difference of only 2.04 %. SRCFST specimen with inner steel tube (SRCFST-T1) exhibits the best impact resistance performance among four types by showing its ability to sustain the highest impact force plateau, the least mid-span deformation and the largest bending moment. Moreover, the size effects on dynamic responses are also investigated. The results show that the key indicators (e.g., the peak impact force, plateau impact force, impact duration, maximum mid-span displacement, and energy absorption) closely align with the standard lines, displaying a maximum deviation of less than 10 %. The traditional similarity law is verified in predicting the impact responses using the scaling factor. Finally, an improved single-degree-of-freedom (SDOF) analytical model is formulated for predicting the displacement responses of SRCFST members under drop weight impact, and it gives an accurate prediction of the displacement response.