Study on the hysteresis performance of X-type round steel pipe stiffening rib coherent node based on microscopic fracture model

Abstract

Abstract The cyclic cavity expansion model (CVGM model) is programmed into the VUSDFLD subroutine of ABAQUS software using the Frotran language to simulate the N-type circular steel tubular joints. Compared with the experimental results, it is found that the finite element simulation is in good agreement with the experimental results, which verifies the feasibility of using the CVGM model to predict the plane circular steel tubular joints. 14 X-type circular steel tubular joints and stiffener-reinforced X-type circular steel tubular joints were designed, The CVGM model was used to predict the fracture of these 14 joints, and the hysteretic behavior of the joints was studied. The results show that when the node is cracked, it is not destroyed immediately, and the node bearing capacity can continue to improve, at which time the hysteretic performance of the node is controlled by the degree of crack extension; The stiffening ribs can improve the ultimate bearing capacity, stiffness, ductility, and energy dissipation capacity of X-type round steel pipe coherent nodes so that the rate of node stiffness degradation is reduced and the seismic performance of the nodes is improved. An increase in the diameter-to-thickness ratio γ of the nodal main tube increases the ultimate load-carrying capacity, stiffness, ductility, and energy dissipation capacity of the coherent nodes of the stiffened rib-reinforced X-type circular steel tube but has a smaller effect on the rate of stiffness degradation; Node branch pipe and main pipe outer diameter ratio β increases, stiffening rib reinforced X-type round steel pipe coherent node of the ultimate bearing capacity, stiffness will increase, but the node ductility and energy dissipation capacity will be reduced, stiffness degradation of the speed of acceleration; Stiffening rib length L increases, the ultimate load carrying capacity, stiffness, ductility, and energy dissipation capacity of the coherent node of X-type round steel pipe reinforced by stiffening ribs will be increased, and the rate of node stiffness degradation will be less affected; The thickness of the stiffening rib tp increase, the ultimate bearing capacity, stiffness, ductility, and energy dissipation capacity of the coherent node of the stiffening rib reinforced X-type round steel pipe will increase, and the effect on the node stiffness degradation rate is small.