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采用ASHRAE晴空模型,利用光线追踪算法编制了基于ANSYS有限元软件的子程序,首次在拱桥温度场计算中实现了太阳辐射、空气对流、长波辐射等环境温度荷载的自动施加。通过与2010年11月7日位于东经108°53′、北纬32°30′的某上承式拱桥现场照片进行对照,验证了该算法可以准确模拟拱上主梁对拱箱的遮盖作用。利用有限元法对该拱桥在当天环境温度荷载作用下,拱上主梁、拱箱的温度场进行了分析。结果表明:在太阳辐射作用下上承式拱桥温度场分布是不均匀的;主梁对拱箱的遮盖作用会导致拱箱温度场分布不均匀,被遮盖位置的温度比太阳直射处温度低;拱桥温度场随太阳辐射强度变化而变化,太阳辐射强度在下午三点时最大,此时刻拱箱顶板上下表面最大温差达到18.5℃。
Using ASHRAE clear sky model, a subroutine based on ANSYS finite element software was programmed by ray tracing algorithm. For the first time, automatic application of environmental temperature loads such as solar radiation, air convection and longwave radiation was realized in the calculation of temperature field of arch bridge. The comparison with the field photos of a certain type of over-arch bridge at 108 ° 53 'east longitude and 32 ° 30 ° north latitude on November 7, 2010 shows that the algorithm can accurately simulate the covering effect of the main beam on the arch. The finite element method is used to analyze the temperature field of arch girder and arch box under the same ambient temperature load. The results show that the distribution of temperature field is not uniform under the effect of solar radiation. The covering effect of the main beam on the arch box will result in the uneven distribution of the temperature field in the arch box. The temperature at the covered position is lower than that at the direct sun. The arch bridge temperature field changes with the change of solar radiation intensity, and the solar radiation intensity is the maximum at three o'clock in the afternoon. At this moment, the maximum temperature difference between the upper and lower surfaces of the dome of the arch box reaches 18.5 ℃.