Research On The Restoring Force Model Of Concrete Filled Double Skin Steel Tubular Columns After Fire

Concrete-filled double skin steel tube members(CFDST)is a new type of composite building component,which use steel tube to replace the reinforced steel structure in concrete.Hollow steel tube structure not only reduces the weight of concrete,but also improves the overall performance and seismic strength of CFDST.CFDST structure also has a good effect on fire prevention.In this paper,the fire resistance and hysteretic performance of CFDST members under the action of ISO-834 standard fire curve under monotonous and reciprocating forces are studied.The work is as follows:(1)According to the hysteresis experiment of concrete filled double skin steel tubular components,the corresponding finite element model was established based on ABAQUS,the simulation to investigate the axial compression ratio,hollow rate,fire time and strength of concrete for fire insulating interlayer concrete-filled steel tube column bending bearing capacity,energy dissipation capacity,displacement ductility and rigidity.(2)Aiming at high temperature in fire situation on hysteresis of insulating interlayer concrete-filled steel tube bending component elements to establish analysis model,the influence of component cross section is analyzed under the influence of high temperature after the bending moment-curvature(M-?),and get the corresponding experimental value,compared with the theoretical value is obtained the consistent relationship between the two.(3)The stress distribution of CFDST structure is analyzed by finite element software of ABAQUS,and the application of various stress distribution to establish real model to the analysis in the process of fire as the change of temperature stress distribution of concrete interface and the interaction force between steel and concrete,analysis on the high temperature when the fire broke out damage for the steel tube of concrete filled steel tube structure and components of stress distribution.(4)Combined with ABAQUS finite element model is given by the bending moment-curvature(M-?)hysteresis skeleton curve graphics to the related influence factors,an analysis of axial compression ratio,the fire time,hollow rate and the influence of concrete strength and other important parameters on the curve is analyzed,combining with the software model of hollow interlayer,the restoring force model of concrete filled steel tubular member is derived.