Seismic Properties Of New Assembled Bolted Dry Joint Unnder Reciprocating Load

The assembled structure is a form of building structure that has been vigorously developed by the state in recent years,which is the way to take the sustainable development of the construction industry and the main means to realize the industrialization of construction.As one of the weaknesses of assembled structures,connection nodes should be considered as the key direction for the study of assembled structures,and the mechanical properties of connection nodes under different loading environments should be studied to contribute to the development of assembled structures.The main work of this paper is to give a specific improvement scheme for a dark bull-leg-inserted rod-angle steel plate beam-column connection node and propose a new assembled bolted dry connection joint.Based on ANSYS/LS-DYNA simulation software,a numerical simulation study of this new bolted dry connection joint PC2 is carried out to explore the seismic properties of this joint under the proposed static low circumferential reciprocating load.The main research contents and results are as follows.(1)The finite element simulation of the new bolted dry joint PC2 was carried out to analyze the stress-strain distribution cloud,load-displacement hysteresis curve and skeleton curve of the joint under low circumferential reciprocal load,and IV to explore the mechanical properties of the joint in terms of load carrying capacity,energy dissipation,stiffness,strength,ductility,and the damage mode of the joint.Two nodal finite element models were also established for computational analysis:the RC cast-in-place node with the same specimen size,reinforcement and loading,except for the different connection node configuration,and the bolted dry joint PC1 before improvement.The simulation results of the three nodal specimens were compared.The results show that the nodal damage mode of all three specimens is nodal failure due to severe concrete damage,but the maximum stress of reinforcement of PC2 joint specimen reaches 473.58 MPa,which is higher than the other two nodal specimens;PC2 joint has better energy dissipation,higher stiffness and strength compared with RC joint and PC1 joint,and its yield load,ultimate bearing capacity and ductility are increased by 35%,22% and 31% respectively compared with RC joint.The yield load,ultimate load capacity and ductility were improved by 35%,22% and 31%,respectively,compared with the RC joint,and38%,27% and 58%,respectively,compared with the PC1 joint,indicating that the seismic performance of the PC2 joint was relatively better.(2)The finite element parametric analysis of the new bolted dry joint was carried out to explore the influence law of different concrete strength,axial compression ratio,angle strength and beam reinforcement rate on the mechanical properties of this joint.The results show that with the increase of concrete strength and beam reinforcement rate,the ultimate bearing capacity,energy dissipation performance and cut-line stiffness of the bolted dry joint increase and have better seismic performance;the increase of column axial pressure ratio in the range of0.65 can improve the yield load,peak load,yield displacement and ductility coefficient of the joint,but the degree of influence is low;the increase of angle strength has no significant influence on the bearing capacity,energy dissipation performance and cut-line stiffness of the joint members before damage.The cut line stiffness has no significant effect.