螺栓连接对输电塔的力学特性的影响研究

发布时间：2018-08-27 15:30

【摘要】：伴随我国的电力建设和经济发展,越来越多的输电塔会途经地基易变形(煤矿开采、冻软土)和极限天气(大风、冰雪灾害)易发生地区,此类地区外部环境因素多变,极易引发输电塔变形甚至损毁。此外,电网电压等级的提高会使输电线路的塔架高度和档距也随之增加,而大跨越输电塔对动载荷的变化更加敏感,因此实际应用中对于动态响应的预测需求也日益迫切。作为由型钢、钢管等杆件连接而成的格构式结构,输电塔的搭建多通过螺栓偏心连接而成。由于螺栓与螺孔之间存在配合间隙,受较大剪切力时,杆件连接处易错动,发生螺栓滑移现象。长期研究表明,在承受较大外力载荷时输电塔的实际变形与传统有限元软件分析结果严重不符,极限承载力的估测判定也尚待考察。动态方面,对输电塔固有频率的预测也与实际有较大偏差。分析其原因,即在有限元建模时对螺栓连接的处理过于简化,刚接或铰接都会使得连接刚度过大,模拟不准确。课题组在之前的研究中,已完成了对典型螺栓连接的轴向拉伸测试,以及对11OkV单回路直线猫头型输电塔的足尺寸试验,包含单根塔腿非均匀沉降工况和固定塔腿的动态测量。在此基础上,本文利用ANSYS软件,先后将塔身斜撑杆件、塔腿主材、塔头杆件的螺栓连接考虑到有限元模型中。针对单根塔腿非均匀沉降工况下的输电塔,重点考察了螺栓非线性滑移曲线的微观滑移刚度和宏观滑移长度两个重要参数对模拟结果的影响,同时针对各部位螺栓连接对输电塔动、静态力学特性的影响进行了详细研究。工程中已发现,预测已经失效的输电塔在实际中常常运行良好。本文就此现象考察了传统模型和考虑螺栓滑移模型在几种非均匀沉降工况下的模拟差异。此外,在输电线路设计过程中为保证安全运行需对沿线的气象环境进行全面的了解以及精确的模拟验算。本文还考察了四种最大工作荷载工况下,考虑螺栓连接对模拟结果的影响,进一步验证了建模时引入各部位螺栓连接对精确预测输电线路的力学响应具有重要意义。本文详细分析了螺栓连接对输电塔力学特性的影响,基于考虑螺栓连接的改进模型,可以对输电塔抗变形、抗振动设计以及安全性评估和治理提出更合理化的建议,也为更加复杂的塔线体系的研究奠定基础。
[Abstract]:With the development of electric power construction and economy in China, more and more transmission towers will pass through the areas where the foundation is easy to deform (coal mining, frozen soft soil) and extreme weather (gale, ice and snow disasters) are easy to occur. External environmental factors in such areas are changeable, which will easily lead to the deformation and even damage of transmission towers. With the increase of tower height and span, the long-span transmission tower is more sensitive to the change of dynamic load, so it is more and more urgent to predict the dynamic response in practical application. The long-term research shows that the actual deformation of the transmission tower is seriously inconsistent with the results of the traditional finite element software analysis, and the estimation of the ultimate bearing capacity is still to be investigated. The reason is that the treatment of bolted connection is too simplified in finite element modeling, and rigid or hinged connection will lead to excessive stiffness and inaccurate simulation. The full-scale test of the head-type transmission tower includes the non-uniform settlement of the single leg and the dynamic measurement of the fixed leg. On this basis, the bolt connection of the oblique strut, the main material of the leg and the head member of the tower is considered in the finite element model by using ANSYS software. The influence of the two important parameters of the nonlinear slip curve of bolts on the simulation results is investigated, including the micro-slip stiffness and the macro-slip length. At the same time, the influence of the bolt connection on the dynamic and static mechanical characteristics of the transmission tower is studied in detail. Good. This paper investigates the difference between the traditional model and the bolt slip model under several non-uniform settlement conditions. In addition, in order to ensure the safe operation of the transmission line, it is necessary to have a comprehensive understanding of the meteorological environment along the line and accurate simulation checking. In this paper, the influence of bolt connection on the mechanical characteristics of transmission tower is analyzed in detail, and the improved model considering bolt connection can resist the deformation of transmission tower. More reasonable suggestions for anti-vibration design, safety evaluation and treatment are put forward, which lays a foundation for the study of more complex tower-line system.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM75

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