Thermal Effect Analysis Of CFST Arches With Rectangular Tube In Sever Cold Areas

Arch bridges with concrete filled steel tube(CFST Arches) have advantages of high bearing capacity, superior plasticity and ductility with better economic performance. CFST Arches with rectangular tube not only contain the advantages mentioned above but also have variable size of corsss section, brief joint structure and convenient for transportation and store which also could avoid the local buckling of steel tube and debonding by arranging the longituditional stiffeners. However there are still many issues of CFST arches to be researched including the thermal effect.Steel and concrete are two main materials of CFST arches which have differenet themal performance, thus causing the themal effect quite different from that of the traditional concrete bridges. China has a vast territory and the meteorological conditions in different bridge sites vaties a lot. It’s unreasonable to apply the same thermal calculation mode in bridges of different districts. This paper focused on the CFST arches with rectangular tube in severe cold area which was characterized by the intense solar radiation and great daily temperature variation. The main research areas were as follows:(1) A summarization of research on CFST arches about temperature problem was presented in this paper as well as the heat conduction theory and calculation methods of solar radiation which laid the foundation of finite element calculating method(FEM).(2) An experimental study of CFST members with rectangular tube was conducted on the bridge site in severe cold area. The results shown that temperature variation in core concrete delayed to the temperature of steel tube which also delayed to the air temperature changing. Longitudional stiffeners in the tube had significant effects on temperature field of cross section which increased the interface area between steel tube and concrete and also increased the minimum temperature of core concrete. A FE model was developed and the calculating results consided well with the tested data, proving the validity of this FE method.(3) This paper analyzed 5 years of meteorological data in Xi’ning and presented relavant thermal parameters in different seasons. A FE model of rib cross section based on background bridges(CFST arches with rectangular steel tube) was developed and the temperature fields of different seasons were obtained. Finally the most disadvantage temperature gradient mode was confirmed, and sensitivity of parameters was studied.(4) A case study was carried out based on the background CFST arch bridge using the presented temperature gradient mode to analyze the uniform temperature effect and gradient temperature effect.