Study On Seismic Performance Of Precast Beam-Column Composite Energy-Consuming Joints

With the vigorous promotion of the state’s green building policies,traditional reinforced concrete structures have shown certain deficiencies due to high energy consumption,long construction cycles,and environmental pollution.Prefabricated structure,as a new type of building structure system,has the characteristics of high construction efficiency and low environmental impact,so it has broad development prospects.However,there are still problems in constructing prefabricated structures,such as excessive on-site wet construction and insufficient ability to repair damage after earthquakes.After summarizing the research achievements of domestic and foreign scholars,this article proposes a composite energy dissipation prefabricated concrete beam-column joint,which adopts dry connections with replaceable energy dissipation damping components and rubber cushion.While leveraging the advantages of prefabricated structures,it can achieve post-earthquake damage repair of the concrete connection.This article uses quasi-static tests,finite element simulations,and theoretical analysis to study the mechanical properties of this type of joint.The main work of the paper is as follows:(1)Summarize the research results of domestic and foreign scholars on prefabricated concrete connection joints and prefabricated energy dissipation connections.Then the design concept of composite energy dissipation prefabricated beam-column joints is proposed in response to the limitations of current prefabricated connections.(2)The mechanical behavior of composite energy dissipation prefabricated concrete beam-column joints was studied using experimental methods.The joint components were designed and manufactured,and low-cycle reciprocating loading tests were conducted to study the mechanical properties and post-earthquake repairability under different design parameters(including the size of energy dissipation components).During the experiment,record the failure process and failure morphology of the specimen;Through experiments,the hysteresis curve of the joint can be obtained.Based on this,mechanical indicators such as the skeleton curve,stiffness degradation curve,ductility coefficient,and equivalent damping coefficient of the joint were extracted.The mechanical indicators under different parameters were first compared and analyzed,and then the mechanical indicators were compared and analyzed before and after replacing the energy-consuming components.The results show that the joint has good seismic performance and a large hysteresis loop area;By using 10mm thick energyconsuming steel plates compared to 8mm thick energy-consuming steel plates,the joint has a higher bearing capacity in the elastic stage,the ultimate bearing capacity of the joints has been increased by 35%,the later stiffness has been increased by 39%,and the energy consumption capacity in the ultimate state has been increased by 13.2%;Replacing the 5mm thick rubber cushion with 10mm can alleviate the stiffness degradation of joints while maintaining the same ductility capacity;Under the elastic and elastic-plastic displacement limits required by the specifications,the damage of the joint is mainly concentrated on the energy consuming components,and the precast beam-column concrete is well protected,indicating that the design of the beam-column joint has achieved the goal and is relatively reasonable.(3)A numerical model of beam-column composite energy dissipation joints was established using finite element software ANSYS and then subjected to cyclic loading to extract hysteresis and skeleton curves,which were compared with experimental results.Then,the bearing capacity gradient analysis was conducted under three parameters:the thickness of energy-consuming steel plates,the thickness of rubber cushion,and the strength of concrete,as well as the sensitivity analysis of the beam-column joint under multiple random parameters.The results show that the simulated bearing capacity curve is in good agreement with the experimental results;As the thickness of energy-consuming steel plates increases,the bearing capacity of joints is also continuously improving,but there is an upper limit to this upward trend;The influence of rubber thickness on the joint’s bearing capacity is relatively small.The sensitivity analysis indicates that in the elastic state,the more sensitive parameters for the joint’s bearing capacity are the elastic modulus of concrete,the compressive strength of concrete,and the elastic modulus of energy-consuming steel components.In the elastic-plastic state,the most sensitive parameter is the yield strength of energy-consuming steel components.(4)The mechanical model of composite energy dissipation assembled beam-column joints was analyzed based on experimental research and finite element simulation.Firstly,a stress-strain function of rubber cushions under uniaxial and eccentric compression was derived according to the rubber’s strain energy density function.Then,based on the interaction relationship between components,the mechanical equilibrium conditions,and deformable compatibility conditions,the bearing capacity function of the coupling forced rubber cushion and energy dissipation steel plate was derived,and on this basis,the load-displacement relationship of the assembled composite energy dissipation joint was finally derived.The theoretical results show consistency with those of experiments and finite element analysis.This theoretical model can estimate the bearing capacity of such beam-column joints under different parameters and will effectively provide a reference for the design of prefabricated composite energy dissipation joints.