Analysis Of Temperature Effect Of Long-span And Half-through CFST Basket Arch Bridge

Because of its simple structure,smaller self weight and quick construction technology,concrete filled steel tube(CFST)composite materials have been widely used in the field of bridge construction,especially for the construction of arch bridges.The combination of steel pipe and concrete not only enhances the bearing capacity of concrete,but also makes up for the unfavorable factors caused by brittleness of concrete due to the hoop action of steel pipe.Due to the existence of the concrete material in the steel pipe,the compressive capacity of the steel pipe is greatly improved,so that the wall thick Ness of the steel pipe,the self weight and the amount of the steel products is reduced in the construction process.Because the arch rib structure of CFST basket arch bridge is always in axial compression state,and because of the complementary advantages of steel tube and concrete,CFST composite materials have unique advantages in the construction of long-span arch bridge.This paper focuses on the temperature effect of Heavy Haul Railway Large Span CFST arch bridge—Longmen bridge in the Yellow River,the actual working environment and construction site specific construction methods to the actual research of long span CFST arch bridge,mainly from the following several aspects of the research:(1)According to the actual working environment of the arch bridge,the relevant thermodynamic parameters are selected and the initial boundary conditions of the heat conduction equation are determined.based on ANSYS finite element software,the thermodynamic finite element model of the arch rib section of the concrete-filled steel tube basket arch bridge is established.the temperature effect of the finite element model on the arch rib section of the concrete-filled steel tube basket arch bridge under the influence of different thermodynamic parameters is studied,mainly the temperature effect under the transient and steady state conditions of the arch rib section of the concrete-filled steel tube basket arch bridge.The research shows that the temperature effect of the concrete filled steel tube section is completely different under transient and steady state changes.due to the change of temperature,the concrete material inside the steel tube will void and stress will be generated inside the steel tube and the concrete,which has a great influence on the structure.(2)The temperature effect of the full bridge of the concrete filled steel tube arch bridge is analyzed by using the ANSYS finite element software and the Midas finite element calculation software respectively.The simplified calculation model of arch bridge is established by using the ANSYS finite element software,and the whole finite element model of the full bridge of the arch bridge is established by using the Midas finite element software.Through the ANSYS finite element software and Midas finite element software,the temperature effect of the full bridge of CFST arch bridge is analyzed,and the results obtained from the two analysis methods are compared and analyzed.The results show that the length of the arch rib of CFST arch bridge increases with the increasing of temperature,and the elevation in the z axis direction of the arch rib position and vault position increases correspondingly due to the restraining effect of arch foot.On the other hand,the elevation of the arch rib position decreases under the cooling effect,and the arch axis and stress state of the arch rib also change with the change of temperature.(3)The influence of temperature load on the stability of CFST arch bridge is preliminarily explored and studied,and the three-dimensional finite element model of the whole bridge is established.Based on this model,the influence of temperature load on the stability of arch bridge is studied.The void of concrete filled steel tube(CFST)caused by temperature load and the stress on arch rib are easy to be destroyed,which affects the stability of arch bridge.