Study On The Bond Properties At The Interface Of Concrete-Filled Cold-formed Steel Tubes

Concrete-Filled Cold-formed Thin-walled Square Steel Tubes(CFST), as a compositestructure, can take full advantage of the mechanical properties of the steel and concretematerial. Load transfer between the steel tube and core concrete because of the existencebond stress, which affects the performance of the combination of components. So far, theimpact of the bond stress on the working mechanism of the components is not entirelyclear. Most of the research on cold-formed steel pipe concrete is around cold-formed steelconcrete. The research of cold-formed thick steel pipe and its "rib form" of concretecolumns is basically blank.In this thesis, on the basis of the existing research results at home and abroad, asystematic experimental study and theoretical analysis of steel pipe concrete interfaceshear bond performance is made to provide a reference for theoretical and applied researchof cold-formed steel pipe concrete structure. The contents are as follows.(1) Analysis to explore the main factors of the impact to square steel tube concreteinterfacial bond strength and qualitative analysis of the relationship between the variousfactors through gray-scale theory;(2) The calculation of the distribution of steel and concrete interface bond stress andbond strength;(3) The relationship between the width-to-thickness ratio of the components of theinterfacial bond strength;(4) Theoretical analysis of transfer length of cold-formed concrete thick steel pipeand the comparison of bond transfer length of various rib form settings of CFST; Therelationship between the form of a rib arrangement and the transfer length.