Seismic Performance And Design Method Of Joint Between Special-shaped CFST Column And H-section Steel Beam

Compared with the column with traditional section,the special-shaped column can provide prominent architectural functions with more indoor space and improve the aesthetic value.However,the reinforced concrete(RC)special-shaped column structure has some limitations.And these limitations make the structure with special-shaped RC column unsuitable for high-rise,super high-rise buildings.The concrete filled steel tubular(CFST)column can significantly improve the mechanical behavior of component without increasing the cross-sectional area of the members.And the structure is suitable for assembly production.Therefore,special-shaped columns are increasingly applied in civil engineering.As a key component in the whole structure,the seismic behavior of beam-to-column joint has great significance.However,there are few researches on the special-shaped CFST column,and there is lack of ystematic design methods,which limits the promotion of the structure with special-shaped CFST column.To investigate the seismic behavior of connection between the special-shaped CFST column and H-section steel beam,experimental and theoretical analysis were carried out in this paper.The research work consists of the following six parts:(1)The pseudo-static test was carried out on ten connections between the T-shaped CFST column and H-section beam,including five connections with U-shaped plate and five connections with vertical stiffener.The test parameters include the stiffening method of column tube,the type of connector and the axial load ratio of column.Based on the test result,the failure mode,bearing capacity,ductility,energy dissipation and stiffness were analysed.The result showed that the load-displacment curves were plump,the bearing capacity and the energy-dissipation capacity were good.These results indicated that the specimens all had good seismic behaviors.(2)Non-linear finite element models which consider the material nonlinearity,geometric nonlinearity,production-induced geometric defects and contact between the steel tube and concrete were established.The results of models were in good agreement with the experimental results,and the reliability of models was verified.The finite element model was used to conducted parametric studies on the bearing capacity of U-shaped plate and vertical stiffener.The parameter analysis results showed that the axial load ratio is the secondary influence parameter,and the size of connector and width-to-thickness of steel tube are the main influence parameters.(3)Based on the results of parametric analysis,simplified mechanical models of the bearing capcity of connectors were established.And calculation formula were proposed,which were in good agreement with the result of finite element models.Then the calculation formulas were further simplified within the range of commonly used parameters,making it suitable for engineering design.(4)The pseudo-static test was carried out on nine connections between the cross-shaped CFST column and H-section beam,including five connections between multi-cell CFST column and H-section beam with vertical stiffeners,two connections between CFST column with stiffening bars and H-section beam with vertical stiffeners and two connections between multi-cell CFST column and H-section beam with stiffening rings.The test parameters includes concrete strength,the stiffening method of column tube,the type of connector and the axial load ratio of column.The result showed that the load-displacment curves were plump,the bearing capacity and the energy-dissipation capacity were good.These results indicated that the specimens all had good seismic behaviors.(5)Non-linear finite element models which consider the material nonlinearity,geometric nonlinearity,production-induced geometric defects and contact between concrete and column tube were established.The results of models were in good agreement with the experimental results,and the reliability of models were verified.The finite element model was used to conduct the parametric analysis of shear strength of joint zone.The parameter analysis results showed that the axial load ratio is the secondary influence parameter,and the height-to-width of joint,the concrete strength and the width-thickness of column tube are the main influence parameters.(6)Based on the results of parametric analysis,simplified mechanical models of the joint zone were established.And calculation formulas of the shear strength of joint zone were proposed,which were in good agreement with the finite element model.Then the calculation formulas were further simplified within the range of commonly used parameters,making it suitable for engineering design.