| During the Northridge earthquake,a large number of brittle failure occurred in beamcolumn connections of traditional steel frames.The researchers designed the plastic hinge away from the beam end to prevent brittle failure and proposed the corresponding forms of connections such as beam-reinforced connection,beam-weakened connection and connection with damper.These connections can effectively prevent brittle failure but there are also some shortcomings.First the bearing capacity of the connection decreases considerably after yielding.Second the range of the plastic zone of the connection can not be effectively controlled,which makes it difficult to repair the structure after earthquake.In order to overcome these shortcomings,a new type of energy-dissipating beam-column connection is proposed.The beam of energy-dissipating connection is broken near the end of the beam and connected through the energy-dissipating section.In order to explore the seismic performance of new energy-dissipating beam-column connection,the following aspects are mainly explored in this paper:(1)The theoretical design of the new energy-dissipating beam-column connection is carried out,including the mechanical index and the size of energy-dissipating components.The geometric model and bearing capacity model of the connection deduce the mechanical indexes of the connection including ultimate bearing capacity,yield force,yield displacement and initial stiffness.In order to meet the design expectation of energy-consuming connection,the design formulas of energy-dissipating component dimensions are given.(2)Six types of connections are tested under cyclic loading and are compared in loadcarrying capacity and energy-dissipating.The new energy-dissipating beam-column connection shows stable bearing capacity and good energy-dissipating capacity.Beam and column remain elastic at a displacement angle of 0.05.Compared with traditional connection,the bearing capacity and initial stiffness of the new energy-dissipating beam-column connection are reduced to protect the beam and column.Because the restraint of the coat to the energydissipating plate,the bearing capacity of the new energy-dissipating beam-column connection maintain stable after connection yielding.Specimen with steel hinge has smaller shear deformation and stronger dissipation capacity.The hysteretic curve of the specimen with web plate with long holes is pinched because of the large slip of the web.The performance of bolted specimen is similar to welded specimen,which proves the reliability of bolted connection in energy-dissipating section.(3)The finite element model is used to verify the theoretical design and proposes four possible failure modes of the connections such as central fracture of energy-dissipating plate,fracture of connection between energy-dissipating plate and backing board,fracture of energydissipating plate at the end of coat,edge fracture of web connecting plate.The parameters of the connection finite element model are analyzed,which shows that increasing the deformation length of the energy-dissipating plate can reduce the ultimate stress,increase the number of bucking waves and make the stress more well-distributed;the width-thickness ratio of the energy-dissipating plate will not affect the performance of connection;increasing the crosssectional area of the energy-dissipating plate and the thickness of the coat can improve the bearing capacity of the connection;reducing the gap between the energy-dissipating plate and the coat can improve the yield force and energy dissipation capacity of the connection;the width of web connection plate mainly affects the flexural capacity of connection and the thickness of web connection plate mainly affects the shear capacity of connection.(4)The pushover analysis and dynamic elastic-plastic time history analysis of steel frame with new energy-dissipating beam-column connection is established by SAP2000.The results show that the energy-dissipating connection can effectively reduce the top displacement,the maximum inter-story displacement angle and the base reaction of the structure. |
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