The Study Of Temperature Effects On Harbin Sifangtai Bridge

As been exposed to natural circumstances, bridge structures are affected directly by some thermal factors such as atmosphere temperature, sunshine etc. Internal forces caused by temperatures allow of no ignorance because this kind of forces probably exceeds those caused by dead loads. Taken Harbin Sifangtai Bridge as object of the research, this paper analyzed the temperature effects upon the internal forces in the bridge. Harbin Sifangtai Bridge is a cable-stayed bridge whose girder is composed by steel I-beam above and concrete deck slab below. Steel I-beam and concrete deck slab perform together by the shear connectors, therefore the difference between the heat properties of steel and concrete effects as one of the main reasons for the emergence of temperature internal forces. Beginning with FEM solution for transient heat conduction, turning to the theory of solar radiation and some heat engineering manuals, utilizing the commercial FEM software ANSYS, the variation regulars to time of temperature field in the standard cross-sections of the composite beam and tower columns of Harbin Sifangtai Bridge have been clarified under the third boundary condition. Making use of the indirect coupling method, the temperature fields from the heat analysis are exerted as temperature loads together with dead loads upon the whole bridge model built by ANSYS for calculation, so how much does the temperature internal forces weigh in the total internal forces can be seen from the comparison of the results of calculation that takes both temperature loads and dead loads in consideration and only dead loads in consideration. Temperature loads are classified into two categories in this paper, one is with the characteristic of temperature's uniform variation in the whole structure and the other one takes temperature's uneven change in different parts of the structure into account under the effect of sunshine. In the finite element model of the bridge, the composite beam and tower columns are meshed with the layered element SHELL91 provided by ANSYS, which makes temperature owns any forms of distribution along the normal direction of the shell element so as to achieve better results in simulation. With the effort of contrasting simulation results to the values of codes for design or data from site, objective and comprehensive appraisement about the effect on composite beam cable-stayed bridge has been put forward in this paper.