Analysis Of Mechanical Performance Of Concrete Incompletely Filled Steel Tube Arch Rib

Concrete-filled steel tube material has been widely applied in construction of arch bribges,due to its high bearing capacticy,excellent plasticity and ductility,convenience of construction,preferabld refractory performance,better economic benefits,ect.However,different degrees of separation between concrete and steel tube inevitably happens for some factors,such as insufficiently pumped concrete,temperature change at outside and shrinkage or creep of the filled concrete.Consequently,separation is one of typical disease of concrete-filled steel tube arch bridge(CFST).Therefore,it is very essential to analyze the separation and cacity effects on mechanical property of CFST struction.Firsty,based on the hypothesis of complete separation between steel tube and core concrete,the separation effects on the structure stiffness and internal force of single-tube and dumbbell-shaped CFST arch rid were researched through the theory of radial load formula.The results of therotical analysis were proved to be correct by calculating some relevant examples.Considering arch rib material nonlinearity and geometric nonlinearity,the finite element models of single-tube arch rib and dumbbell-shaped arch rib were established respectively.The influence of parameters such as separation ratio,steel ration,rise-span ratio and the way of load on the ultimate bearing capacity of single-tube arch rib and dumbbell-shaped arch rib were analyzed.Finally,a CFST arch bridge with a span of 125 m was employed as an example.Based on ANSYS beam element model,the effects of factor which contains separation ratio and steel ratio on the stiffness of CFST arch rid and bearing capacity of bridge were discussed in this research.The results show that the stiffness of single-tube CFST arch rid after complete separation is not affectd;while the resuls of dumbbell-shaped CFST arch rib are changed obviously.With the increase of separation ratio,the bearing capactity and stiffness reduce significantly for CFST arch bridge,and the degree of reduction is related to the parameters such as the de separation ratio,steel ration,rise-span ratio and the way of load and so on.