Study on temperature gradient parameters of hollow members of bridge structure

At present, the specifications of bridges of railways and highways prevailing in china do not take into account the influence of the difference between the north and south climates on the temperature action of bridge and instead provide roughly defined regulations about curves of falling temperature gradients. In view of the above deficiencies, by analyzing the meteorological data of Harbin(1963~2002) and Guangzhou(1997~2006) and by establishing the finite element model, the paper studied the parameters of temperature gradients of hollow members of large-scale bridges generated in daylight temperature rising and cold-wave temperature falling. In respect of the daylight temperature rising action, the extremum prediction formula for temperature difference is put forward and simplified, which can be used to distinguish the difference of temperature actions in different areas and provide reference for establishment of temperature action zones. In respect of the cold-wave temperature falling action, qualitative analysis is made on the influence of the thickness of the pier wall on the temperature difference extrema and the curve of temperature gradients and the extremum prediction formula for temperature difference is put forward. The research results as follows: the extremum of the temperature difference in daylight temperature rising is 35°C for Harbin Area and 20°C for the Guangzhou Area, therefore it is necessary to consider the effect of climate condition and set up temperature action zones; the thickness of the wall of members affected by the cold-wave temperature falling action is about 0.6 m and exponential coefficient of the temperature difference curve decreases with the increasing of the thickness of the wall of members.