Research On The Time Effects Of Concrete Filled Steel Tube Arch Bridge And The Proposed Analysis Method

Concrete Filled Steel Tube is a typical composite structure style, due to the merits of high bearing capacity,high speed of constitution,good fire resistance performance and good econimical benefit, it is widely used in high-rise,super high-rise buildings and bridge structures in recent years, and tend to be used in more higher and severe situation. But as a new structural type, further researches are needed on its various properties, just like the time-dependent behaviour. Time effects could affect the behavious of structures or structural elements significantly at serviceability stage. The code or specification in various countries introduce the adjusted coefficients in design to consider creeep and shrinkage and the methods are not unified at present. Consequently, it is crucial to establish the method for the time analysis in CFST structures.This paper expounds the essence of creep and shrinkage of concrete, the commonly used calculation mode is introduced, based on this, the characteristics of time effects of CFST and improvement of calculation mode are discussed; FEM equation to calculate creep internal force in statically indeterminate structures and derivation process are given, and the application in arch structures is stated; basic theories of creep and shrinkage are comparatively analyzed, the AEMM and Transformed Section Method are combined to deduce the formula of redistribution between concrete and steel in uniaxially loaded and beam-column element; to simplify the calculation, several subroutines are compiled to solve the structural creep internal force and stress redistribution in the composite cross section in CFST arch bridges, and a simple example is used to implement the programme. The relative theories could be a reference for further studies in the field.