Study Of Stability Characteristics Of Long-Span CFST Tied-Arch Bridges

A through tied-arch bridge is a type of built-up arch structure, characterized by the horizontal thrust of arch end being balanced by its ties. With the development of CFST in bridge construction, nearly in the past one hundred years, CFST tied-arch bridge has being widely applied all over the world. The span becomes longer and longer. But the development of the theory of CFST tied-arch bridge did not keep up with that of the application in practical project. With the increase of span, the stability problem of the tied-arch bridge became more necessary. The theory of constitutive relation of CFST has being in research, which makes the study of tied-arch bridge more complex.The finite element program is applied to investigate the stability characteristics of long-span CFST tied-arch bridges, and in addition the various influence parameters are considered and compared. Some conclusions useful to the design of this kind of bridges are obtained. The main contents are as follows: Firstly, a software is designed to generate the ANSYS commend stream for stability analysis of tied-arch bridges visually by VC++, which makes the analysis process more simple. Especially for geometrical-material double non-linear analysis of ultimate bearing capacity of tied-arch bridges, the analysis process became very convenience.Secondly, study of elastic stability characteristics of CFST tied-arch bridges. Based on the analysis of elastic buckling of Nan-He Bridge, the influence of collar beam stiffness to horizontal stability and end floor beam to lateral stability have been discussed in this paper. Some proposals useful to the design of this kind of bridges are obtained.Thirdly, study of ultimate bearing capacity of CFST tied-arch bridges. Geometrical-material double non-linear analysis of ultimate bearing capacity of Nan-He Bridge was performed firstly, and some influence parameters were studied after that, such as constitutive relation of CFST, steel ratios and the stiffness of arch ends. Based on the analysis and study, some proposals useful to the design of this kind of bridges are obtained.