油气管道跨越桁架结构应力分析

Stress analysis on crossing truss structures of oil and gas pipelines

为了获得安全、经济、可靠的桁架模型,避免重复设计,提高设计质量和效率,以青海油田分公司跨越桁架标准化设计项目为背景,研究小型跨越桁架结构的受力状态,主要针对构件选型、截面选型、节点相贯线、结构内力、变形、刚度等方面进行对比分析,并采用MIDAS/CIVIL大型有限元软件建立有限元模型,研究影响桁架结构内力的因素。研究表明:综合考虑桁架结构的应力、挠度、刚度变化趋势,可以得到"理想桁架";对于以恒载为主控荷载的桁架结构,当不断加大桁架的宽度和高度时,结构自重不断增加,导致结构杆件应力、变形均增大,对结构受力不利,也不经济,因此,建议桁架设计时选择合理的外形尺寸,兼顾桁架结构的受力及经济性。

In this paper, the stress state of small crossing truss structures was investigated with the standardization design program of crossing truss of Qinghai Oilfield Company as the background, so as to build up a safe, economic and reliable truss model, avoid duplicate design and improve design quality and efficiency. Comparative analysis was mainly performed on component selection, section selection, joint intersection, internal force, deformation and rigidity. The finite element model was established by using MIDAS/CIVIL large finite element software. And finally, the factors influencing the internal force of truss structures were analyzed. It is shown that the ideal truss can be obtained by analyzing the change tendency of stress, deflection and rigidity of truss structure comprehensively. As for the truss structure with dead load as the master, its own weight increases with the increasing of its width and height, which consequently results in the increase of stress and deformation of truss members. It is adverse to the structural stress, and also uneconomical. Therefore, it is suggested to choose reasonable external dimensions when the outline dimensions of truss are designed. Moreover, both the stress and economy oftrnss stmctttres should be considered.