Experimental Study On Seismic Behavior Of Earthquake-resilient Steel Joints With Replaceable Bucklingrest-rained Links

Traditional steel structure is prone to brittle fractures occurred in welded steel beamcolumn joints under earthquakes.To solve the abovementioned problems,relevant researchers designed various types of new-designed steel beam-to-column joints by intentionally transferring the plastic hinge to the outside of the panel zone,and rapid repairment of the joint can be realized by replacing damage-concentrated elements.Buckling restrained braces has been widely used in practical engineering due to its excellent energy dissipation capacity.In this paper,a new type of steel frame beam-tocolumn joints(RBRL-ERSJ)were proposed,which introduced the buckling restrained mechanism into the replaceable damage-concentrated element joints.In order to study the RBRL-ERSJ joints proposed in this paper,a total of 9 full-scale joints were designed and tested under quasi-static loads,during which three parameters are investigated: the web connection type,the core plate stiffeners,the web connection type,buckling restrained forms,the connecting plate thickness and loading laws.Based on the analysis of the test phenomenon,the damage rule and failure mechanism of the joint were obtained.Bearing force of the loading point,displacement and strain of the key parts of the joints were collected to analyze hysteresis curves,skeleton curves,energy dissipation capacity,deformation mode and stiffness degradation of the joints.The test results show that all test pieces proposed in this paper can control the damage within the replaceable links beyond the major components,expect for the comparative test group,and it is convenient to replace after tests,which achieved the expected design goal.When the web connection of RBRL is hinged of bolted,and buckling restrained mechanism with compression gap at the end,the joint has excellent performance.Due to manufacturing error,slippage were detected during the loading process when the web connection type of RBRL is hinged.However,this kind of specimen still has good seismic performance.It is worth noting that when the web connection type of RBRL is rigid,the joint suffered tearing behavior,which leads to the shear transfer to the core plates and other components outside the web,affecting the energy dissipation capacity of the core plates.The finite element software ABAQUS were adopted to simulate the proposed RBRL-ERSJ joints.The results of the comparative test show that the modeling method provided in this paper can simulate the hysteretic behavior well under cyclic loads.On the basis of the test results,the influence of different parameters on the seismic performance of the joints were further discussed,and reasonable design suggestions were given.Based on the test results,this paper proposed the strength and initial stiffness calculation method of RBRL-ERSJ joint,and theoretical skeleton curve of the joint were put forward,which were used to make comparison with tests and finite element skeleton curves.The results show that the three skeleton curves are in good agreement.Finally,the calculation method and design suggestions of the flexural capacity of the joint were give in this paper,which can provide reference for further research.