Study On The Thermal Field And Thermal Effect Of Box Girders

In engineering practice, the box-section beam perennial exposed, and subject to a variety of natural environmental conditions change, the temperature of surface and internal of structure changes at any time, we need long-term observations of temperature field in box girders. However, as many random factors and the lack of test results, it is difficult to guarantee the reliability of test results, a large number of specimens and the long-term observation for the engineering design is not the economy, the time is unacceptable. It is therefore necessary to rely on computer simulation analysis as a method of engineering design support.This paper describes the hazards of Concrete Box Girder due to temperature effect, as well as the work done by scholars at home and abroad in this respect. The basic theory of heat transfer and heat transfer finite element method are explained . This paper also brings forward to the method to deal with the boundary conditions of box beam and to calculate the sun radiation intensity and location of the sunlight. According to box-girder temperature field test data, the author analysises the temperature distribution of the box girder and simulates box-girder temperature field through the contrast of measured and theoretical values proved that the method adopted by this paper is feasible. Through a number of calculation,the author analysises the influence of some factors such as the orientation of box girder, radiant heat absorption, wind speed, temperature changes and other factors outside of the box-shaped beam , identifies the most disadvantaged temperature field and calculates maximum stress, the maximum deflection and lateral displacement. on the basis of the analysis, proposes temperature gradient specifications to the section similar to the magnetic levitation rail box girder beams the temperature gradient patterns.