Research On Seismic Performance Of Embedded Side-Plate Joint Between Walled Concrete-filled Steel Tubular Column And H-Section Steel Beam

Concrete-filled steel tubular columns are widely used in multi-story and super highrise steel structure buildings owing to their characteristics such as advanced seismic performance,excellent economy and ease of construction.However,when used in residential buildings,the columns will protrude outside the wall and affect the comfort of the residents.Therefore,our research group proposed walled concrete-filled steel tubular column(hereinafter referred to as walled column).Compared with concrete-filled steel tubular column,walled column can be embedded in the building walls to prevent them from protruding indoors.As the key force-transmitting component of the frame system,the beam-column connection will directly affect the seismic performance of the frame system.Therefore,it is of great significance to study the mechanical properties and design methods of beam-column joints.Due to the lack of research on walled column-steel beam joints,especially the lack of design methods that can guide engineering applications,it is very unfavorable for the promotion of walled column systems.This paper proposes embedded side-plate joint between walled concrete-filled steel tubular column and Hsection steel beam.Through experimental research,finite element research and theoretical analysis,the seismic performance and design method of embedded side-plate joint are systematically studied.The main work and research results of this paper are as follows:(1)Taking the central column joint of the frame system as the research object,six full-size specimens of embedded side-plate joint were fabricated to perform low-cycle reciprocating load pseudo-static tests.The test parameters are as follows: the length of the extended part of the side plate,the thickness of the side plate,the height of the side plate and the connection form of the side plate,etc.Through careful analysis of the test process and failure characteristics of the specimens,the failure modes of the embedded side-plate joint were proposed;based on the load-displacement curve obtained from the experiment,the ductility,energy dissipation capacity,bearing capacity degradation,stiffness degradation and other indicators of this type of joint are studied.The test results show that the reasonably designed embedded side-plate joint has good ductility and seismic performance.(2)A refined finite element model of the embedded side-plate joint between walled column and H-section steel beam is established.The finite element model considers many non-linear factors,including plastic damage of the in-filled concrete under reciprocating loads,the restraint effect of column steel tube on the inner concrete,material nonlinearity,geometric nonlinearity and initial geometric defects,etc.The results obtained by the finite element model analysis are in good agreement with the test results,which verifies the reliability of the finite element model.(3)Numerical simulation of quasi-static loading is carried out on the embedded sideplate joint,which is used to study the force transmission mechanism of the joint.Through the finite element analysis method,the influence of key parameters on failure mode is analyzed,the effect of the external length of the side plate,the thickness of the side plate,the height of the side plate,the axial compression ratio and other parameters on the seismic performance is studied.(4)Considering the contributions of the steel tube web side,the steel tube flange side and in-filled concrete,the force transmission mechanism in the panel zone is revealed.Based on the data of the finite element analysis of the embedded side-plate joint,the calculation formulas for the shear bearing capacity of the panel zone are proposed.The calculated results of the formulas are consistent with results of the finite element.(5)On the basis of the aforementioned experiment and finite element study,the internal force transmission path of the beam end of the embedded side-plate joint is analyzed,and the calculation formula of the joint flexural bearing capacity is given;Based on experimental research,finite element simulation and theoretical analysis,the construction measures and design method of embedded side-plate joint are systematically proposed referring to the current relevant codes in China,which could be applied for engineering application.