Separation Effects On Mechanical Behavior Of Concrete-Filled Steel Tubular (Single Tuble) Arch Rib

Because of their advantages such as longer span,higher capacity,less weight and being convenient for construction etc,concrete-filled steel tube(CFST)arch bridges develop rapidly in china in the recent years.Along with the increasing of the span,people are more concerned about the gaps in the interface between the core concrete and steel tube. This dissertation developed a series of case study and theoretical analysis to the separation effects to mechanical behavior on CFST arch bridge. The following are main research contents and achievements:(1) This dissertation proposed complete debonding calculation model of CFST arch rib.Based on the assume of complete debonding on the interface between steel tube and filled-concrete,the conclusions of model analysis are that:For constant-section single tube CFST rib,section total internal force on the situation of complete debonding is equal that of on the situation of complete bonding,moment ratio of steel tube and filled-concrete on the situation of complete debonding are equal to bending stiffness ratio of them. This dissertation derived the calculation formulations for calculation internal force distribution of steel tube and filled-concrete.By using the method of structural mechanics, this dissertation proved the rsults of mode lanalysis were right.(2) Based on the assume of complete debonding on the interface between steel tube and filled-concrete,the conclusions of model analysis are that:For constant-section single tube CFST rib,interface complete debonding basically will not lead to reduction of structure stiffness. Based on the calculation model of complete debonding on the interface between steel tube and filled-concrete,this dissertation theoretically researched the change of stiffness of CFST rib by using principle of virtual work, and proved the rsults of mode lanalysis were right.(3) This dissertation proposed partly debonding calculation model of CFST arch rib.By analysing the calculation model of partly debonding on the interface between steel tube and filled-concrete,the results showed that:Partical separation effects on mechanical behavior of whole arch rib was very small.(4) Based on separation effects on mechanical behavior of concrete-filled steel tubular arch rib,this dissertation proposed a systematic method to solve this problems.