Parametric Study On The Mechanical Behavior Of The Self-Centering Circular Concrete-Filled Steel Tubular Column To Steel Beam Exterior Connection

The seismic design of the traditional structure is mostly ductile design.Although it can ensure that the structure does not collapse with a large probability,the main structure will generate irreparable damage due to dissipating seismic energy.After the earthquake,the main structure is difficult to repair and often needs to be demolished and reconstructed,thus causing huge economic loss.As a kind of earthquake resilient structure,self-centering structure can reduce the residual deformation after earthquake and quickly restore the function of the structure.Since the self-centering structure was introduced,it has attracted extensive attention from researchers at home and abroad.At present,the research on self-centering structure mainly focuses on steel structure and reinforced concrete structure.As an important structural form,the combined structure has little research on its self-centering ability.The concrete-filled steel tubular column-steel beam frame structure has a high strength and good ductility,and is a typical combined structure.The connection between the beam and column is the key to structural stress.In order to reduce the residual deformation of concrete-filled steel tubular column to steel beam frame structure after earthquake,a kind of self-centering circular concrete-filled steel tubular column to steel beam connection with web friction device is proposed.the main research works are as follows.(1)A new type of self-centering circular concrete-filled steel tubular column to steel beam connection with web friction device is proposed,the construction form of the connection is introduced.The mechanical performance of the connection is analyzed theoretically,including the connection components behavior,the moment-relativerotation model and the lateral load-displacement model of the connection under cyclic loading,and energy dissipated of the connection.(2)One full-scale connection is tested under cyclic lateral load,the results indicated that the connection has good self-centering and energy dissipation capacity,the momentrelative rotation curve were observed to have a double-flag shape obviously.A generalpurpose non-linear finite element analysis program(ABAQUS)was used to build the numerical model of the connection,the accuracy of the finite element model is verified by comparing the experimental results with the finite element simulation results and the theoretical calculated values.(3)The main parameters of the connection were analyzed,including the prestress force of the Post-tensioned high strength strands,the bolt prestress force,the position and the number of the Post-tensioned high strength strands.The results indicated that the above parameters have obvious influence on the performance of the connection.The analysis results show that the initial stiffness,critical opening bending moment and selfcentering ability of the connection increase with the increase of the prestress of the steel strand,and the residual deformation of the joint decreases with the increase of the initial prestress of the steel strand.The energy consuming capacity of the connection increases as the bolt prestress force increases.The position of the strand has essentially no effect on the mechanical behavior of the connection.When the total prestress force of the Posttensioned high strength strands is equal,increasing the number of strands can effectively increase the stiffness and load carrying capacity of the connection.In this paper,a new type of self-centering circular concrete-filled steel tubular column to steel beam connection with web friction device is proposed.Through theoretical analysis,experimental research and finite element parameter analysis,the mechanical behavior of the connection is systematically studied.The mechanical performance of concrete-filled steel tubular column-steel beam connection is provided as a reference.