Study On Tensile Behavior And Design Methods Of Concrete-filled Stainless Tube Member

Concrete-filled stainless steel tube(CFSST)is a steel-concrete composite structural component formed by filling concrete in stainless steel tube.It has excellent corrosion resistanced and mechanical properties.At present,many studies on the mechanical properties of CFSST members under compression or bending or combined compression and bending have been carried out by researchers at home and abroad,while there are few reports on the tensile properties of CFSST members.In practical engineering,CFSST members may be subjected to axial or eccentric tension.Based on the above background,this paper carries out experimental and theoretical analysis of CFSST members subjected to axial and eccentric tension and analyzes the influence of different parameters on tensile behavior of CFSST members.The parameters include thickness of steel tube,compressive strength of core concrete,load eccentricity,bond or unbonded between the steel tube and core concrete.Then,the finite element analysis model is established.The whole process mechanical behavior of CFSST specimens subjected to tension is analyzed with the test results,and the interaction between steel tube and core concrete is studied.The influence of different parameters on tensile strength of CFSST and the applicability of the existing formula for calculating the tensile strength to CFSST specimens are analyzed.The main conclusions are as follows:(1)Core concrete can effectively restrain the shrinkage of stainless steel tube and make steel tube be in three-direction stress state,which improves tensile strength of steel tube under tension.The tensile strength of CFSST members under axial tension is about 15% higher than that of stainless steel hollow tubes.The increase of tensile strength of CFSST members decreases under eccentric tension,and the reference range is 1%~6% in this paper.(2)Finite element analysis results show that stainless steel tube is the main force component of CFSST members,and core concrete plays the role of supporting stainless steel tube.It demonstrates that stainless steel tube and core concrete canwork well together under tension.When there is no bond between steel tube and core concrete or the load eccentricity increases,the interaction between stainless steel tube and core concrete is enhanced,but the compressive strength of core concrete has little influence on it.(3)The thickness of steel tube and load eccentricity are the main factors of affecting the tensile strength of CFSST specimens,and compressive strength of core concrete and interface bond between stainless steel tube and core concrete have little influence on the tensile strength of CFSST members.Existing formulas for calculating the tensile strength are suitable for CFSST members.Among them,the formulas in European Code EC4(2014)and Han Linhai's revised model have good accuracy.