| In recent years,with the advantages of high production efficiency,high degree of industrialization,less on-site wet work and less environmental pollution.The prefabricated building has gradually become a hot spot in the research and development of construction industry in China.However,compared with the cast-in-place structure,the reliability of the joints has a greater impact on the energy dissipation capacity,which restricts the engineering application of prefabricated buildings to a certain extent.The PRESSS project put forward a precast prestressed concrete frame structure in American,which has been applied in foreign countries.It is found that the structure can not only meet the needs of the development of prefabricated building structure,but also meet the requirements of building structure for seismic performance.However,the domestic research and application of the joint form are few in China,and the numerical simulation and stiffness analysis of the joint also need to be further studied to investigate the seismic mechanism of the joints.Based on the structural form,two kinds of precast prestressed concrete frame joints with different energy dissipation were designed,such as the joint with internal energy dissipation steel bar and the joint with external dissipater which adopted the replaceable energy dissipation devices.Through the combination of low-reversed cyclic loading test,numerical simulation and theoretical analysis,the influence of the two different energy dissipation designs on the seismic performance of the precast prestressed concrete frame joints were discussed.This research can supplement the theory of numerical simulation and initial rotational stiffness of the joints,and provide a theoretical basis for its engineering application.The following conclusions were obtained:（1）Through the low-reversed cyclic loading test of the two precast prestressed concrete frame joints with different energy dissipation designs,the seismic performance indexes of the joints were analyzed,such as energy dissipation capacity,failure mode,stiffness degradation,strength degradation,displacement ductility and residual deformation of the joints.The test results show that:the concrete failure of the two joints were mainly occurred at the end of the beam,the crack between the beam and the column were closed after unloading,the two joints all have good self-centering capacity.The hysteretic curve of the joint with internal energy dissipation steel bar is fuller.However,the insufficient anchoring of the joint with external dissipater caused the energy dissipation device exiting work early,which has a certain impact on the energy dissipation capacity of the joint.But the joint with external dissipater has higher bearing capacity and initial stiffness,and all of the two joints have good ductility,strength and ability of resistance to deformation.（2）Based on the problem of insufficient anchorage of the support of the external dissipaters in the test,a kind of support for fixing the dissipaters was put forward.The closed connection between the support and the end of the dissipater can effectively fix the dissipaters.The support can not only ensure the energy dissipation capacity of the dissipaters,but also replace the dissipater easily,which can reduce the cost of structural repair and improve the timeliness of structural repair.（3）The numerical simulation analysis of the test joints was carried out.After verifying the rationality and correctness of the numerical model,the parametric analysis of the prestress value and the diameter of the energy dissipation section to the joint with external dissipater were carried out.The results show that:When the prestress value increases from 20%fptk to40%fptk,the energy dissipation capacity of the joint was significantly improved,and continue to increase the prestress value is not conducive to the energy dissipation of the joint;When the diameter of the energy dissipation section is 10 mm～16 mm,the deformation mainly occurred on the energy dissipation section.When the diameter of the energy dissipation section is 18 mm and 20 mm,the deformation mainly occurred on the end of the energy dissipation section and the connecting steel plate.Reducing the diameter of the energy dissipation section did not significantly reduce the bearing capacity,but it helps to make the deformation of the energy dissipation reinforcement can occurred on the energy dissipation section,so as to reduce the deformation of the connection between the end of the dissipaters and the support,and ensure the reliability of the connection between the external dissipaters and the support.（4）The mechanical mechanism of two precast prestressed concrete frame joints with different energy dissipation designs was analyzed.Based on the analysis of the stress state and stiffness of the two joints,the calculation formula of the initial rotational stiffness of the two joint were proposed.The theoretical values of the initial rotational stiffness were obtained by calculation,which are close to the experimental values,and the rationality and correctness of the formulas were verified.By comparing with the definition of semi-rigid joint in Eurocode3:Design of Steel Structures（EC3）,it is found that the two joints with different energy dissipation designs are semi-rigid joints,which can effectively transfer bending moment and shear force,and have good resistance to deformation. |
