| The construction of CFST arch bridge in China has developed rapidly since the 21st century.CFST arch bridge is also gradually moving towards the pace of long-span,followed by its long-term performance has become one of the significant factors affecting the development of the bridge type.The creep of concrete is an unavoidable problem in the long-term development of the structure,and the creep has a significant impact on the time-dependent behavior of the structure.The research on creep of concrete has been going on for nearly a hundred years,but there is no definite conclusion.The creep is an important problem in CFST arch bridge theory,which as a branch of the research on creep of CFST structure.This paper analyzes the uncertainty and certainty of CFST arch bridge based on the creep effect of CFST arch bridge under self weight.The main contents of this paper are as follows:(1)The creep theory and creep model of concrete-filled steel tubular structure are described,and the research on creep theory and model of concrete-filled steel tubular structure is extended.This paper introduces the research status of CFST structure in China and abroad,the Monte Carlo stochastic finite element method,Latin hypercubic sampling method and the sensitivity analysis method in the probabilistic analysis of structural creep e ffect.(2)The three-dimensional finite element model of the Daxiao Jin bridge of the long-span concrete-filled steel tube arch bridge is buit.,and the static state of the bridge under its own weight is analyzed,and the static results of the main arch ring under its own weight and its distribution in the whole bridge are obtained by extracting the important values of deflection,axial force and stress.(3)The creep model under different codes is selected to analyze the creep effect under the dead weight of the bridge.The creep effect analysis of the structure under the dead weight for about three years is considered,and the creep law is analyzed from the deflection,axial stress and stress of each time history.The results show that the creep growth rate is the fastest in the first half of the year,and it tends to zero in about three years.The deflection increased by 37.33%,the axial stress and stress of steel tube increased by 42.2%,and the axial stress and stress of concrete decreased by 22.42%compared with the case without considering creep.The creep results of the two models show that the creep coefficient of the creep model of CFST arch bridge in the creep coefficient of the standard in 2015 is smaller.The difference percentage of deflection stress and other results is about 20%compared with the normal reinforced concrete creep model of the standard in 2018.(4)The uncertainty of creep effect is studied by taking geometric dimension and material properties as variables.The main factors affecting the creep deflection,internal force and stress are summarized in the sensitivity analysis.The conclusion shows that the elastic modulus of concrete and the uncertainty coefficient of creep model have the greatest influence on the positive and negative correlation. |
