Reseach On Temperature Field And Creep Effect Of Concrete Filled Steel Tube Arch Bridge

Concrete-filled steel tube (CFST) arch bridge, which is a burgeoning type of bridge structure, has been popularized and developed rapidly in the past twenty years in China because of its advantages:light self-weight, beautiful model, super spanning ability and convenience in site work. However, the studies on theories of CFST arch bridges get relatively behind the engineering practice at present. In particular, the research on the temperature and creep was not sufficient, and the need to further researches is obvious.In this thesis, a practical bridge was taken as the project background. Adopting the field test, the temperature field distribution law of CFST arch rib cross-section is discussed. Then, the initial temperature distribution curve along the diameter direction of CFST cross-section at the most unfavorable temperature difference obtained from fitting the measured data processing. Based on the finite element analysis of temperature field, and the theory of heat transfer, solar physics and general astrology, the mechanism of heat transfer between steel and surroundings, between steel and core concrete is studied. The boundary conditions of heat transfer in CFST arch bridges subjected to solar radiation are systematically defined. Arch rib cross-section temperature field is simulated by the FEM package ANSYS as the running software platform. The results show that:with the change of the solar radiation and the air temperature, the temperature distribution of concrete-filled steel tube cross-section behaves the characteristics of nonlinearity in time and space. At the same time, the contrast of measured and theoretical values proved that the method adopted by this thesis is feasible.In creep, firstly, the common concrete creep prediction models at home and abroad are introduced in detail. Some aspects about each model such as the creep factors considered, the function structure forms, the forecasting accuracy are also comprehensively analysed and evaluated. Then, the creep calculation theory and methods, and the characteristics of CFST creep are presented. Finally, on the basis of the bridge creep effect analysis methods, combined with the engineering example, the influence of creep on CFST arch bridge displacement and stress is analyzed by MIDAS as the running software platform. The results prove that: in the long-term loads, the influence of creep on CFST arch bridge is a much substantial increase in the deflections and a significant redistribution of sectional stress, and most of these effects have been appeared in the early period of finished stage, less later effects. In addition, through calculation and analysis, using different concrete creep prediction models have a great influence on CFST arch bridge displacement and stress. It is recommended that the study on the value of CFST creep coefficient should be carried out by a lot of tests and come into being standardized form to guide design and production work.