Dynamic behavior of concrete-filled steel tube cantilever columns stiffened with encased carbon fiber reinforced plastic profile subjected to lateral impact load

Abstract

The impact behavior of building and bridge structures is already a growing concern due to the frequent occurrence of vehicle collision accidents. Concrete-filled square steel tube stiffened with encased I-shaped carbon fiber reinforced plastic profile (CFST-CFRP) is suitable for building and bridge structures due to its high bearing capacity and small section size. Thus, this study experimentally and numerically presents the dynamic responses for CFST-CFRP columns under lateral impact to evaluate their impact resistance. Firstly, three CFST-CFRP columns and one CFST column were tested in a rigid vehicle impact device, with variations in impact velocity, impact type, impact impulse of the rigid vehicle, and CFRP profile. The impact force-displacement curve and failure mode of CFST-CFRP columns were obtained. Additionally, finite element analysis (FEA) models were built by ABAQUS and verified against tested results. Then, the working mechanisms of CSFT-CFRP columns under impact load were further revealed in-depth by analyzing displacement, impact force, inertia force, bending moment, shear force, and dissipated energy. Based on the working mechanisms, the effect of the CFRP profile on the dynamic response of CFST-CFRP member subject to different parameters was discussed. The results indicated that all the specimens fail at the support. With the additional CFRP profile in the CFST column, the failure pattern of the steel tube was transformed from fracture to local buckling. CFRP profiles enhance the impact resistance of CFST columns (incremented by 17%), and the increasing ratio rises with the decreasing steel ratio and steel strength of members. Steel tubes can share 72% and 78% of energy absorption and bending moment, which is the main impact-resistant component. For this study, valuable experimental data can be supplied for CFST-CFRP columns subjected to vehicle collision. Meanwhile, a theoretical reference for impact resistance design in the future is also provided.