| The concrete-filled steel tube(CFT)beam-column is a structural form in which the steel pipe and the concrete are combined.The steel pipe has a restraining effect on the core concrete,and in return the presence of the concrete can delay the local buckling of the pipe.This interaction can compensate for their own shortcomings.Therefore,it has the advantages of high bearing capacity.good plasticity and toughness,strong energy dissipation capacity and good seismic performance.In the actual project,the use of circular CFT column is more than the square one.Due to the limited confining effect of the square steel pipe on the core concrete,it limits its application and development in engineering seismic resistance.In this,a new structure scheme has been proposed in this paper,namely adding rids at the end of CFT beam-column.This can improve the effect of the square steel tube on the core concrete and improve its seismic performance.In order to study the seismic performance of CFT column with ribs at the end thoroughly.Three CFT beam-columns with end ribs have been designed and produced.Pseudo static test has been conducted,and seismic behavior indicators like the bearing capacity.hysteresis curves,skeleton curves and displacement ductility have been obtained.Compared with the conventional ones,experimental results indicate that the load-displacement hysteretic loop curve of specimens is more full.The decline of the skeleton curve is flatter.The limit displacement increases obviously.increased by 44.4%.65.3%and 29.3%respectively.The displacement ductility coefficient increases obviously.respectively increased by 27.0%.51.3%and 6.7%.The beam-columns with ribs exhibit good energy dissipation capacity and significantly improved seismic performance with larger ductility.What’s more,the finite element analysis software ABAQUS is used to establish a reasonable finite element model.The seismic behavior of CFT column with ribs is analyzed under different parameters(the axial compression ratio,the wall thickness of steel tube).The analysis results show that under the condition of constant wall thickness of steel pipe,with the increase of axial compression ratio,the ductility of the member is obviously reduced.Under the condition of constant axial pressure,with the increase of the wall thickness,the ductility is improved remarkably.After that,the structural requirements of end stiffener are analyzed theoretically.The analysis results show that the setting of ribs must meet two basic principles.On this basis,the specific construction measures of the end rib are proposed. |
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