Research On Creep Effects Of Concrete-Filled Steel Tube Arch Bridge

Beginning in the1990s, our country set off a construction boom of concrete-filled steel tube (CFST) arch bridges, but the design theories are relatively backward compared with the engineering practice, such as the creep of CFST arch bridges have always been the issues of concern to engineers. The creep of CFST is different from that of common concrete, because the core concrete of CFST is in the airtight condition and multi-axial stress state, interacting with steel tube. The main results of research are presented as follows:1. As the elastic modulus of concrete development with age considering, the analysis of creep effects of CFST arch bridges is achieved by finite element software MIDAS/Civil, and the creep coefficient can be defined by yourself, the creep effects of construction phase also have been considered.2. The analysis of creep effects on CFST arch bridge in creep model of CEB/FIP1990、CEB/FIP1978、ACI209show that, the creep effects of CEB/FIP1978model are the largest of the three models in same condition, the creep effects of CEB/FIP1990model are closer to that of ACI209model.3. Through creep test, this paper gets the creep curves of CFST and plain concrete under long-term load, the creep of core concrete is less than that of plain concrete, and put forward creep coefficient expression suitable to core concrete.4. The creep effects of CFST arch bridge were calculated by this paper’s creep coefficient expression, and the sensitivity of the parameters was analyzed, then discussed the impact of different dead load, section stiffness (steel ratio), concrete-pouring time to creep effects of CFST arch bridges.