鱼腹式截面温度场边界条件及温度梯度分析

Analysis of Temperature Field Boundary Conditions and Temperature Gradient in Fish Belly Section

根据日照条件下鱼腹式截面梁各部位的热边界条件不同,提出一种分区计算热边界条件的方法。将鱼腹式截面分为四个区域,按照第三类边界条件,计算考虑斜面天空效应影响的各区域的热边界参数,并研究斜腹板倾角对鱼腹式截面温度效应的影响。采用数值仿真方法进行瞬态温度场分析,通过分析最不利温度分布,拟合得到鱼腹式截面梁体横向、竖向、厚度方向的指数型温度梯度函数,并与规定的温度梯度进行对比分析。结果表明:斜面天空效应对鱼腹式截面温度分布影响较大,而分区计算热边界条件能较好地反应斜面天空效应对鱼腹式截面温度效应的影响;鱼腹式截面温度场效应受斜腹板倾角影响较大;拟合的温度梯度较规定的温度梯度能更好地反映底板与顶板之间的温度差,更符合于鱼腹式截面实际的温度场分布。

According to the different thermal boundary conditions of each part of fish-belly section beam under sunshine,a method for calculating thermal boundary conditions in different areas was proposed in this paper.Firstly,by dividing the fish-belly section into four regions,the thermal boundary parameters of each region considering the influence of the inclined sky effect were calculated according to the third type of boundary conditions,and the effects of inclined web angle on the temperature effect of fish-belly section were discussed.On this basis,the transient temperature field analysis was conducted by using numerical simulation method.By analyzing the most unfavorable temperature distribution,the exponential temperature gradient functions in the transverse,vertical and thickness directions of the fish-belly section beam were fitted,and compared with the temperature gradient specified in the bridge code.The results show that the inclined sky effect has a great influence on the temperature distribution of the fish belly section,while the zoning calculation of thermal boundary conditions can better reflect this influence on the temperature effect of fish belly section.The inclined web angle has an important influence on the temperature field effect of the fish bellied section.The fitted temperature gradient in this paper,which can better reflect the temperature difference between the bottom and top plates than the temperature gradient specified in the bridge code,is more in line with the actual temperature field distribution of the fish belly section.