Behavior Of Eccentricity Loaded Circular Stainless Steel-carbon Steel Composite Tube Confined Concrete Columns

The proportion of steel structures and composite structures in the construction system will gradually increase in the background of strong government support for green and assembly buildings and the serious over-production of steel.In traditional steel structures or steel-concrete composite structures,the steel members have the weak points of crossion.If the stainless steel-carbon steel composite tubes are applied instaed of carbon steel tubes,the corrosion problem would be resolved without increasing the expense significantly.The stainless steel-carbon steel composite tube is used to replace the carbon steel tube in the traditional steel tube confined concrete columns,and the new type of stainless steel-carbon steel composite tube confined concrete column possesses the good points of high load-carrying capacity,good ductility,crossion resistance and so on.This kind of new members have good application prospect.In the past,the research on the composite tube confined concrete columns was mainly focused on the axially compressive behaviour of the stub columns.Up to now,there is no research work about the eccentrically loaded behavior ot this kind of new member.To clearly understand the behavior of this member under eccentric laod,in this paper,the unaxially loaded performance of stainless steel-carbon steel composite tube confined concrete is studied by test and finite element analysis.The main contents are as follows:(1)Fifteen stainless steel-carbon steel composite tube confined concrete short columns were tested,including 5 stainless steel-carbon steel composite tube confined concrete short columns under axial load,6 stainless steel-carbon steel composite tube confined concrete short columns under eccentrical load and 4 concrete-filled composite steel tube short columns.The strain on the steel tube at the critical point and the development of the whole deformation of the specimens were recorded and analyzed.The mechanism of the specimens was also studied.The experimental results showed that the specimens possessed good ductility becaused of the confinement of composite steel tube,while the capacity decreased obviously with the increasing of eccentricity.(2)Fifteen stainless steel-carbon steel composite tube confined concrete medimu columns were tested,including 4 stainless steel-carbon steel composite tube confined concrete columns under axial load,7 stainless steel-carbon steel composite tube confined concrete columns under eccentrically load and 4 concrete-filled composite steel tube columns.The strain on the steel tube at the critical point and the development of the whole deformation of the specimens were recorded and analyzed.he mechanism of the specimens was also studied.The results showed that the composite steel tube confined concrete long column under eccentrically loads had high bearing capacity and good ductility,and the steel tube could restrain the concrete beyond the peak load to improve the ductility of the specimen.(3)The finite element software ABAQUS is used to develop the numerical model of the stainless steel-carbon steel composite tube confined concrete medimu columns,whose accuracy was validated by comparing with the experimental results.Then the influence of diameter-to-thickness ratio,slenderness ratio,eccentric ratio,and ratio of thickness of stainless steel-to-carbon steel was analyzed.At last,the experimental results and calculated results based on finite element model are used to check the exsisting design methods of carbon steel tube confined concrete members.