高原环境下大跨空间网架结构日照非均匀温度效应研究

Research on Non-uniform Temperature Effects of Sunlight in Large-span Space Grid Structure in Plateau Environment

网架结构是一种空间大跨度结构,在温度荷载和边界约束作用下,杆件产生应力,结构发生位移,因此在网架结构设计过程中应考虑温度荷载的不利影响以保证结构的承载性能和正常使用.基于西藏山南隆子机场航站楼项目,以高原环境温差大、风速大、太阳辐射强的特点为背景,对航站楼屋面大跨度空间网架结构在均匀温度场和非均匀温度场作用下的温度效应进行研究.利用Midas Gen有限元软件对该屋面网架进行建模,获取不同工况下的结构响应.研究结果显示,承载能力极限状态下,考虑均匀温度荷载时网架结构杆件的最大应力比和网架结构最大位移均大于未考虑均匀温度荷载.正常使用极限状态下,恒荷载与活荷载对网架结构的最大位移起控制作用,而均匀温度荷载对结构的最大位移影响较小.结构最大应力出现在支座位置处,最大位移出现在网架外伸悬挑处,但都未超过规范规定的限值,且非均匀温度场对结构应力和位移的影响较均匀温度场更为明显.根据日照对网架结构的作用规律,给出相应施工方面的建议,以减少温度效应对网架结构施工过程的影响.总之,高原环境下,大跨空间网架结构的设计施工以及使用过程中不仅要考虑到均匀温度场的影响,也应考虑到非均匀温度场的影响,以保证结构的安全和正常使用.

The grid structure is a kind of long-span space structure.Under the action of temperature load and boundary constraint,the bar will produce stress and the structure will displace.Therefore,the adverse influence of temperature load should be considered in the design process of the grid structure to ensure the bearing performance and normal use of the structure.Based on the terminal project of Longzi Airport in Shannan,the temperature effect of the long-span space grid structure of the terminal roof under uniform temperature field and non-uniform temperature field is studied on the background of high temperature difference,high wind speed and strong solar radiation in the plateau environment.Midas Gen finite element software is used to model the roof grid to obtain the structural response under different working conditions.The results show that under the ultimate state of bearing capacity,the maximum stress ratio of the bar and the maximum displacement of the grid structure considering the uniform temperature load are greater than those without considering the uniform temperature load.Under the limit state of normal use,the constant load and the live load control the maximum displacement of the grid structure,while the uniform temperature load has little effect on the maximum displacement of the structure.The maximum stress of the grid structure occurs at the support position,and the maximum displacement of the grid structure occurs at the overhanging cantilever of the grid,but both do not exceed the limit value specified in the code.The influence of non-uniform temperature field on structural stress and displacement is more obvious than that of uniform temperature field.According to the action law of sunshine on the grid structure,the corresponding construction suggestions are given to reduce the influence of temperature effect on the construction process of the grid structure.In short,in the plateau environment,the design,construction and use of large-span space grid structure should not only consider the influence of uniform temperature field,but also consider the influence of non-uniform temperature field,so as to ensure the safety and normal use of the structure.