Study On Seismic Performance Of Assembled Replaceable Artificial Plastic Hinges And Their Composite Joints

The fabricated steel-concrete composite structure meets the target requirements of green and healthy development and high seismic performance,and has received more and more attention and application.Under the action of earthquake,the damage and destruction of beam-column joints often lead to the difficulty of repairing the whole structure after the earthquake,resulting in serious economic losses.Based on this,this paper proposes a kind of replaceable artificial plastic hinge composite joints(RAPHCJ),which fully combines the performance advantages of artificial plastic hinges,replaceable damaged parts and fabricated steel-concrete composite structures to achieve the functional objectives of joint concentrated damage and energy consumption,protection of the main structure and post-earthquake recovery.On the basis of quasi-static test and ABAQUS finite element analysis of prefabricated replaceable artificial plastic hinge specimens,this paper optimizes the design of prefabricated replaceable artificial plastic hinge composite joints,and conducts seismic performance research through low-cycle reciprocating load tests.The main research work and achievements are as follows:(1)The seismic performance of five fabricated replaceable artificial plastic hinge specimens was studied through low cycle reciprocating load tests.The main parameters include replaceable flange connecting plates,shear energy dissipation rods,and friction plates.The results show that each specimen undergoes plastic rotational deformation at the pin shaft where the steel beam is connected to the artificial plastic hinge,and the ultimate failure mode is beam end bending failure,mainly manifested in the buckling failure of the replaceable flange connecting plate and the shear deformation of the shear resistant energy dissipation rod.The artificial plastic hinge connecting the main structure is in an elastic state as a whole.Under low cycle reciprocating loading,the hysteretic curve of the assembled replaceable artificial plastic hinge is relatively full,and the skeleton curve presents a trend of elasticity,elastic-plasticity,and plastic strengthening.The equivalent viscous damping coefficient is between 0.24 and 0.40,with good energy dissipation performance.In addition,increasing the strength and thickness of the replaceable flange connecting plate can significantly improve the seismic characteristics of the specimen,such as load-bearing and energy consumption performance.The pre tightening torque of the shear energy dissipation rod has a certain impact on the bearing capacity and initial stiffness.Failure to install friction plates will accelerate the shear deformation response time of the shear energy dissipation rod,improve the bearing capacity and strength stability of the specimen.(2)The feasibility and accuracy of the finite element model are verified by comparing the finite element analysis results with the test results.On this basis,the influence law of the thickness and strength of different replaceable flange connection plates,the diameter and porosity of shear dissipation rod on the seismic performance of prefabricated replaceable artificial plastic hinge was further analyzed.The results show that when the prefabricated replaceable plastic hinge fails,the stress is mainly distributed in the replaceable flange connecting plate,shear dissipation rod and beam end arc plate at the joint of pin shaft.Strengthening the thickness and strength of the replaceable flange connecting plate can improve the bearing capacity and energy dissipation performance of the specimen.If the diameter of the shear dissipating rod increases or the porosity decreases,the hysteretic performance of the specimen can be effectively improved.It is recommended that the diameter be larger than 12 mm and the porosity of the dissipating rod be controlled within the range of 0-2mm.(3)Based on the study of prefabricated replaceable artificial plastic hinge,three specimens of prefabricated replaceable artificial plastic hinge combination joints were designed,and the effects of the thickness of the replaceable flange connection plate and the pretightening torque of the shear dissipating rod on the seismic performance of the prefabricated replaceable artificial plastic hinge combination joints were analyzed.The results show that the failure position of prefabricated replaceable artificial plastic hinge joint is ideal,the plastic hinge position is controllable,the deformation energy dissipation and damage are mainly concentrated on the replaceable parts,and the core area of the node has no obvious damage,which meets the performance requirements of controlling the failure form of the node,protecting the main structure and quick post-earthquake repair,and has good hysteretic performance and ductility performance.Increasing the thickness of the replacable flange connecting plate can obviously improve the bearing capacity,stiffness degradation and strength degradation performance of the composite joint,but the final failure form is the failure of the core area of the joint,and the ductility deformation ability decreases.Reducing the preloading torque of the shear dissipating rod can improve the ductility,energy dissipation and bearing capacity of the specimen,and improve the stiffness degradation and strength degradation of the joint.It is recommended to reduce the pre-tightening torque of the shear dissipation rod and the thickness of the replaceable flange connecting plate is less than 14 mm.