The Research On Shrinkage Creep And Temperature Effect Of Concrete Filled Steel Tubes On Long-span Arch Bridge

With the rapid development of the transportation of our country, the construction of bridge has thrived and a variety of large-span bridges have been constructed. Concrete-filled steel tubular(CFST) arch bridge, which is a new type of bridge structure, has been popularized and developed rapidly in the past ten years in China because of its advantages: light self-weight, beautiful scenery and super spanning ability. However, the study on design theories of CFST arch bridges becomes relatively behind the engineering practice at present. Especially on the research about the creep and shrinkage of concrete, the temperature stress under the temperature load.This thesis has its project background from a middle-type CFST arch bridge- Maocao Street Bridge of Yiyang, China. The work is part of"The key techniques of the design, construction and maintenance of concrete-filled steel tubular arch bridges", launched by the Science and Technology Project of Construction of the West Traffic. The main research contents are as follows:(1) Made a general introduction of the features and the development situation of the CFST use in arch bridges briefly; then summarized the late theory research situation of the CFST arch bridge and introduced the analysis theory of shrinkage and creep in CFST arch bridges and the coefficient of concrete creep definition in various countries.(2) Through long-time observation of the CFST component in the indoor environment, we obtained the shrink and creep curve of plain concrete and CFST; then we analyzed the test result, obtained the regularity and characteristic of the shrink and creep of CFST. The CFST components developed relatively slow, and their average shrink amount is only 30% of the plain concrete ones of the same age. The creep results of plain concrete were used to estimate the creep coefficient formula of the core concrete in CFST.(3) Using the large-scale finite element software, we built a spatial simulating model of Yiyang Maocao Street Bridge, China. Exerting temperature load to the model, we calculated the temperature effect on CFST and the internal force change regularity of the CFST arch bridge under the effect of different temperature loads.(4) A more than one-year period creep observation on Maocao Street Bridge was carried out. By analyzing the survey data and comparing with the theory results calculation, which was based on the creep coefficient theory concluded from the indoor test, we obtained the creep regularity of the CFST arch bridge, verified the exactness of the expression formula of the creep coefficient fitted. Through calculation of the finite element model, we obtained the influences of creep on the strength characteristic and redistribution of sectional stress of the CFST arch bridge.