Experimental and theoretical investigation on the impact dynamic response of CFDST-K joints under different structure-related parameters

Abstract

K-joints have been commonly used in steel structures benefiting from excellent connection performance. In this study, a combined experimental and nonlinear analysis was performed on CFDST-K joints to investigate the displacement, strain evolution, bearing capacity degradation, impact force, and energy absorption capacity in detail with different structure-related parameters such as hollow rate and steel tube thickness. The finite element model was developed and validated by experimental results. Results indicated that the CFDST-K joint can effectively enhance impact resistance with a more reasonable energy distribution. To improve the anti-impact property, the optimal hollow rate is 0.63 and the diameter-to-thickness ratio of the outer tube should be less than 30. Meanwhile, the inner tube thickness had little effect on impact resistance under low-impact energy. Finally, simplified calculation methods for the deformation and impact force were derived based on a parametric study on the dynamic response by discussing the influence of the impact energy, hollow rate, diameter-to-thickness ratio, and axial compression ratio. The findings can serve as a foundation for the development of more reliable CFDST-K joints for steel structures.