Research On The Seismic Performance Of Circular Tubed RC Column-RC Beam Frame

Tubed RC columns has the characteristics of high bearing capacity,good deformation capacity and excellent seismic performance,which is suitable for multi-highrise structures and has broad application prospects.At present,scholars at home and abroad mainly focus on the study of steel-tube confined concrete at the level of columns and joints,but not at the level of structural system such as Circular Tubed RC ColumnRC Beam Frame.Based on the existing research results of tubed RC columns and joints,and taking the beam-column stiffness ratio as the main parameter,this paper designed two trusses of plane frame of Circular Tubed RC Column-RC Beam.The main work contents are as follows:(1)The pseudo-static test of a two-story,two-span plane frame with tubed RC columns-RC beam under vertical constant load and horizontal reciprocating load was carried out,and the frame met the requirements of "strong column and weak beam".Due to the insufficient lateral support stiffness,the ultimate failure mode of the truss frame specimen was the out-of-plane instability of the side column.However,the plastic hinge at the end of the beam was almost all found,which can still reflect the stress mechanism of Circular Tubed RC Column-RC Beam Frame.(2)Based on the experiment,the framework crack,deformation mechanism and failure mode of the specimens were observed,get such as load-horizontal displacement hysteresis curve,a load-steel strain relationship curve,the load-steel pipe strain relationship curve,etc,analysis of node and the plastic hinge region reinforced with the development of the stress of the steel tube,to explore the mechanism of energy dissipation and stiffness degradation of system.The test results show that the failure of Circular Tubed RC Column-RC Beam Frame which meet the requirements of "strong column and weak beam" begins with the reinforcement yielding at the bottom end of the beam,and the plastic hinge at the end of the beam increases with the increase of the loading displacement.The load-displacement hysteresis curve of the specimen is relatively full and Circular Tubed RC Column-RC Beam Frame has good deformation and energy dissipation capacity.The annular stress at the end of the steel tube develops sufficiently,which exerts sufficient restraint on the core concrete.(3)The finite element model was established with ABAQUS software,and the finite element results were in good agreement with the test data,thus verifying the effectiveness of the finite element model.Based on this model,the finite element parameter analysis is carried out to provide design Suggestions for practical projects.(4)Finite element parameter analysis based on the model,the analysis parameters include axial compression ratio,diameter to thickness ratio,concrete strength,steel pipe strength and column reinforcement ratio.The results show that the axial pressure ratio has a great influence on the ductility of the frame.The diameter to thickness ratio of steel tube,the strength of steel tube and the reinforcement ratio of column have little influence on the frame in the elastic stage,but have certain influence on the elastoplastic behavior of the frame.