Experimental Research On The Anti-seismic Profermances Of A New Precast Prestressed Concrete Frame Joint With Groups Of Energy Dessipation Bars

Over the past decade,the process of building industrialization has been in full swing in China.With the characteristics of easy standardization,stereotyping and modularization,the precast concrete structure greatly improves the construction speed,reduces the labor intensity,guarantees the quality of engineering construction,conforms to the concept of green environmental protection,and therefore develops rapidly.Based on the Natural Science Foundation-Seismic Performance and Design Method of Locally Prestressed Precast Concrete Frames With Groups of Energy Dissipation Bars(51678136),this paper summarizes the types of beam-column joints of precast concrete structures,compares the main precast structure systems that can be put into production in China in many aspects,and through the literature review of domestic and foreign scholars in the seismic performance of beam column joints on the research history and ideas.On this basis,a new type of longitudinal weakening bar buckling restraint energy dissipation device developed by our research group,energy dissipation bar,is introduced into the precast joint,and a new type of Prestressed Precast Concrete Frames joint with groups of energy dissipation bars is proposed.In order to study the anti-seismic performance of the new type of precast concrete joint,two groups of precast corbels,ordinary concrete and UHPC,with different groups of energy dissipating bars,were designed in this paper,and five groups of full-scale specimens were tested under quasi-static load.The crack development and failure modes of the specimens were observed and recorded during the test.The hysteretic curve,skeleton curve,yield load and yield displacement,ultimate load and ultimate displacement,strength degradation table,stiffness degradation curve,one-cycle and cumulative energy dissipation value,prestress value change curve,self-reset coefficient,beam-column interface deformation were obtained by processing the test data.The seismic performance indexes of five groups of specimens are evaluated by degree analysis and draw the following main conclusions:(1)The new type of joint has good anti-seismic performance.The hysteretic curves of the five groups of specimens are full and the energy dissipation capacity is strong.All the anti-seismic performance indexes meet the requirements of the code.(2)The performance of UHPC corbel is better than that of ordinary concrete corbel.(3)The stiffness,bearing capacity,ductility,self-resetting capacity and energy dissipation capacity of the new type joints will be significantly affected by different energy dissipation bars groups and prestressing force.(4)By synthesizing several indexes,YZ-2,which consists of two energy-dissipating rods with a length of 150 mm in weakening section,has the best comprehensive performance,stable bearing capacity,large ductility,full hysteresis curve,strong energy-dissipating capacity and good self-resetting performance,and has the most popularization and application value.OpenSees is used to simulate the new type of precast joint by finite element method,and the simulation results are in good agreement with the test results.With the help of finite element software,the parametric analysis of the prestress value of the joints,the converted cross-section area of energy dissipation bars and the axial compression ratio are carried out,and the relationship between the above parameters and the performance of the joint is obtained.Finally,the research contents and results of this paper are summarized.According to the test results,suggestions for improvement of this new type of joint are put forward,and the problems that need further study are prospected.