Research Of Seismic Performance Of Precast Prestressed Sleeve Connected Frame Joints

Prefabricated building is a new type of structure which is popularized in our country and it is an important way to realize the industrialization of architecture.The study of precast concrete frame joints is the key to the development of prefabricated buildings.The paper proposes a new type of precast prestressed sleeve connected frame joints,based on the results of prefabricated joints in foreign countries.The seismic performance of the joints is studied through low-cycle cyclic loading test.The main work and results are as follows:(1)Summarizing the research achievements of the prefabricated frame joints and the research status of grouting sleeve connection technology at domestic and overseas,on the basis of which a new type of precast prestressed sleeve connection frame joints is proposed.(2)The full grouting rotary rolling roller selected for the production in the manufacture of the joint specimen is introduced.The sleeve is made of low alloy seamless steel pipe material and is rolled by mechanical rolling with special machine tools and the inner and the inside and outside of the sleeve form helical rib.Four groups of 12 sleeve joint specimens are made and the axial tensile tests are carried out.The load-displacement curve residual deformation and failure pattern of the sleeve joint are studied.The results show that the bearing capacity and deformation of the sleeve joint can meet the requirements of domestic industry specification under the condition that the anchor length of steel bar is not less than 8times of the diameter of steel bar.Based on the universal finite element software ABAQUS,three sleeve joint models with different diameters of reinforcing bars are established.The load deformation curves and the stress values under the limit load are calculated.The results are in good agreement with the test results and the correctness of the modeling method is verified.(3)The design concept and test purpose of prefabricated prestressed sleeve connection frame joints are described.One cast-in-place joint and three prefabricated joints with different diameter common energy dissipation bars are made.The main points in the process of joint construction,specimen fabrication and assembly of test loading scheme and measurement contents are introduced.(4)The low cycle cyclic loading tests of four test joints are completed,and the experimental phenomena and results are described.The stress state,destructive mode,hysteretic curve,skeleton curve,energy dissipation and stiffness degradation of the four test joints are compared.The results show that the precast prestressed sleeve connected frame joints can have good energy dissipation and self-reset ability through the allocation of common energy dissipation steel bars with reasonable cross-section area.(5)Based on the experimental data,the dimensionless skeleton curve model of three prefabricated joints under low cycle cyclic loading is obtained by using the experimental fitting method,and the relationship between the pinching points in the hysteretic model is determined.Finally,the formula of stiffness degradation rule is obtained by regression.