Expansive concrete is used in the steel tube of Concrete-filled steel tubular(CFST)columns to solve the problem of steel-to-concrete debonding.Self-stress is generated between concrete and steel plate due to concrete ...Expansive concrete is used in the steel tube of Concrete-filled steel tubular(CFST)columns to solve the problem of steel-to-concrete debonding.Self-stress is generated between concrete and steel plate due to concrete expansion,which can effectively improve the mechanical performance of CFST columns.Deformation tests were conducted on concrete and CFST columns,respectively.The free deformation of concrete and circumferential deformation of steel tubes were measured and analyzed.A calculation method was proposed to evaluate the hoop strain,self-stress and creep deformation of the CFST columns.The test and calculation results indicate that the proper addition of expansion agent in the internal concrete can keep concrete expansive and generate self-stresses for a long time.The expansion and self-stresses prevent the debonding between the steel tube and the internal concrete.Increasing the dosage of expansive agents and reducing the curing age both increase the expansive deformation and self-stress of CFST columns.Increasing the tube thickness reduces the expansive deformation and increases the initial self-stress of CFST columns.展开更多
基金The National Key R&D Program of China(No.2017YFC0703705)the National Natural Science Foundation of China(No.51778183)Jiangsu Planned Projects for Postdoctoral Research Funds(No.2020Z088).
文摘Expansive concrete is used in the steel tube of Concrete-filled steel tubular(CFST)columns to solve the problem of steel-to-concrete debonding.Self-stress is generated between concrete and steel plate due to concrete expansion,which can effectively improve the mechanical performance of CFST columns.Deformation tests were conducted on concrete and CFST columns,respectively.The free deformation of concrete and circumferential deformation of steel tubes were measured and analyzed.A calculation method was proposed to evaluate the hoop strain,self-stress and creep deformation of the CFST columns.The test and calculation results indicate that the proper addition of expansion agent in the internal concrete can keep concrete expansive and generate self-stresses for a long time.The expansion and self-stresses prevent the debonding between the steel tube and the internal concrete.Increasing the dosage of expansive agents and reducing the curing age both increase the expansive deformation and self-stress of CFST columns.Increasing the tube thickness reduces the expansive deformation and increases the initial self-stress of CFST columns.
