Experimental Research On Bond Interface Properties Of Concrete Filled Steel Tube Columns Considering Creep And Interfacial Corrosion

The bond strength and bond-slip relationship have important influence on the mechanicalproperties of concrete filled steel tubes(CFST). The study on the bond-slip behaviors at theinterface of CFST has profound theoretical significance and practical value, and it is furtherconcerned by construction engineers. In the service period, the interface between steel andconcrete has the inevitable corrosion, especially in winter, People sprinkle deicing salt inorder to clear the snow from the deck, which causes the CFST interfacial corrosion.Simultaneity, the interface has the inevitable initial imperfections, when under external loads,these initial defects continue to accumulate and develop, resulting in interface bondingperformance degradation, the structural capacity decline. Therefore, It is necessary to explorecorrosion quantity and interface damage of the impact on CFST properties in this paper.In this paper, we deeply study the CFST interface bond performance both inexperimental and theoretical. This test is divided in two parts, firstly, the axis push-out testdesigned with the parameters of corrosion quantity was carried out. Subsequently, the test wasdesigned with the basic parameters of sustained loading of time.The research work is summarized as follows:1. In order to explore the mechanical properties affected by interface corrosion, the testthat14specimens designed with the parameters of corrosion time and diameter-thicknessratio were carried out, obtaining P-s curves and examining CFST interface bond performance.2. In order to research the mechanical properties affected by sustained loading, the testthat7specimens designed with the parameters of sustained loading time was carried out,examining CFST interface bond performance.3. Based on the model of a thick wall cylinder, the law between corrosion expansiveforce and corrosion quantity was analyzed. Through the carbon steel of corrosion mechanismin NaCl environment, we probe the interface bond performance on the different stages of thecorrosion products, obtaining the relationship between bond strength and corrosion quantity.4. Based on the ACI(1992), each test piece under sustained loading of the concrete creepstrain were obtained. Applied the method of the damage mechanics, the interface damagevariation was defined, and established the relationship between the concrete creep strain anddamage.The bond-slip constitutive relationship between Steel pipe and concrete that interfacedamage were regressed. The damage of mechanism under sustained loading was analyzed.