| A new type of prefabricated column-column steel connection is proposed and its seismic performance is tested.Prefabricated column-column steel connection is mainly composed of prefabricated upper column,prefabricated lower column and replaceable steel connectors.High-strength bolts and unbonded prestressed bars are used to connect the column-column steel connection,and a brass friction energy dissipator is set on the web of the steel connectors to realize the energy dissipation capacity of the components.Angle steel with stiffening ribs is arranged on both sides of the flange of the steel connector to achieve the function of connection and energy dissipation,and at the same time to achieve the ability of aftershock resistance and can only replace the function of Angle steel to restore the structure after small and medium earthquakes.The structure is easy to assemble and has excellent seismic performance and self-reset ability.In this paper,seven groups of specimens were tested under low cyclic loading,and the seismic performance and restoring force of the steel connectors were compared and studied when the two sides of Angle steel were not replaced,the two sides of Angle steel were replaced,and the two sides of Angle steel were replaced simultaneously with the new tensioned prestressing steel.The failure mode,hysteresis curve,ductility,energy dissipation capacity and other test results of the specimen are analyzed.The main research contents are as follows:(1)The new prefabricated column-column steel connector has excellent seismic performance and self-reset effect.Its seismic capacity is reduced but it performs well during secondary loading,and it can effectively resist aftershocks after earthquakes.The function of the structure can be basically restored to the original level after the replacement of the Angle steel,and the replacement of the Angle steel after the earthquake is simple and quick,and the seismic performance can be better recovered after the retensioned prestressing.(2)Increasing the axial compression ratio can significantly improve the bearing capacity of the specimen,but the residual deformation is larger.Compared with the specimens reloaded without changing Angle steel and reloaded with changing Angle steel,the difference of seismic performance decreases with the increase of axial compression ratio.However,excessive thickness of Angle steel will lead to fracture of Angle steel in the late loading period,resulting in a decline in bearing capacity,which is not conducive to aftershock resistance and recoverability of structural performance.(3)By using the degenerate trilinear model and mathematical fitting method,combined with the test and theoretical analysis,the three characteristic points of steel connectors,namely linear limit point,peak load point and loading limit point,are determined,and the hysteresis rules are formulated.The restorative force model of the new precast assembly column-steel connection is proposed,and the comparison with the test skeleton curve is made to verify the good agreement of the restorative force model,which provides a theoretical basis and reference for the design method of the new precast assembly column-steel connection in the later stage. |
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