Stress Performance And Optimization Analysis Of A New Type Of Low Multilayer Assembly Concrete Beam Column Joint

In recent years,the waste of resources and environmental pollution caused by the construction industry has gradually caused social dissatisfaction.Faced with this,the country decided to vigorously promote the development of prefabricated buildings.Prefabricated buildings have many advantages,such as saving resources,protecting environment,reducing costs and so on.The development of prefabricated buildings in foreign countries has been very mature,but in our country,it is still in the primary stage.What restricts the development of prefabricated buildings in our country is the connection of beam-column joints of assembly structure.It can be said that the research and development of beam-column joints with excellent performance is the key to promote the development of fabricated buildings.Fabricated connection of beam-column joints is mainly divided into wet-type connection and dry–type connection.In our country,there are many researches in wet-type connection and few researches in dry-type connection,the existing form of dry-type joints is single,and there are deficiencies in performance respectively.Based on these,this paper puts forward two kinds of new dry-type connection forms of fabricated beam-column joints,and then studies the performance of each form and optimize design for joints.In this paper,the ABAQUS finite element simulation of two new types of joints under low cycle reciprocating cycle load is carried out.The stress-strain hysteretic curves of the joints are studied and analyzed,and the design of the joints is improved according to the results of analysis.Then,the effects of several key parameters on the hysteretic curve,skeleton curve,bearing capacity,strength and stiffness degradation,ductility and energy absorption are studied in detail,and the design of joints is optimized.Finally,this paper compares the two new joints and analyzes their advantages and disadvantages.Through a series of researches and analyses,the main conclusions are as follows:?1?The two new types of beam-column joints after improvement and optimization have large bearing capacity,no obvious"pinch phenomenon"and hysteretic curves are full.What's more,there is no obvious degradation of the same level of strength,and the ductility and energy absorption capacity of the two new beam-column joints are better than those of common cast-in-place concrete structures.The results show that the two new joints are of good comprehensive performance.?2?The hysteretic loop,bearing capacity ductility and energy dissipation of the new type one of joints are greatly affected by the size of the corbel.The shorter the length of the corbel is,the greater the bearing capacity will be.However,the less full the hysteretic curve is,the weaker the ductility and energy dissipation will be.If the corbel is too high,it will weaken the shear resistance of notched beam protruding,and if it's too short,it will weaken the overall bearing capacity of the joint.In this paper,when the height is 200mm and the length is200mm,performance of the joint is better.In addition,the distance between beam columns is very important,and only when the distance is 4mm,performance of the joint will be better.?3?Size of the corbel has little influence on new type two of joints.When the length of the upper corbel keeps the same,increasing or decreasing the length of the lower corbel will not cause obvious changes in the hysteresis curve,bearing capacity,ductility and energy consumption of the joint,but the length of the upper corbel should not be too short.When the lower corbel keeps the same,the greater the bearing capacity of the joint will be,but the weaker the ductility and energy absorption capacity will be.?4?After optimization and analysis of parameters,the optimal size of joint one is H₂₀L₂₀D₄ and the optimal size of joint two is X₃₀₀S₂₀₀Q₁₀₀.Joint one and joint two have their own advantages and disadvantages in performance.The energy absorption capacity of joint one is enhanced by the anchor bars passed through the precast beam,while the bearing capacity of joint two is increased by the corbel.