【作者】 杨俊涛；

【导师】 楼文娟；

【作者基本信息】 浙江大学 ， 结构工程， 2011， 硕士

【摘要】 大跨越输电塔线体系可以跨越山川河谷等障碍,四回路钢管大跨越输电塔有四层横担,具有占地面积少、输送电力多的特点。由于四回路钢管大跨越输电塔塔身高度高,横担长度长,这使得塔线体系在环境荷载作用下的极限承载能力与普通塔线体系有所不同。大跨越输电塔线体系承受的环境荷载主要有风荷载、雨荷载以及覆冰荷载。本文主要研究雨荷载对输电塔的作用以及大跨越输电塔线体系在环境荷载下的极限承载能力。针对雨荷载的数值模拟,首先解决风速入口的问题：本文采用谐波叠加法,生成空旷场地的脉动风速时程,并以此作为流场模拟入口；其次要解决雨颗粒的模拟问题：利用离散相模拟雨滴,用离散涡模型模拟瞬态流场；最后求解雨滴荷载,根据冲量守恒定理,得到时间间隔为0.25s的平均雨荷载时程。结果显示：当降雨强度为709.2mm/h,风速为10m/s时,平均雨荷载与风荷载比值最大值为2.53%,出现在18m高度处；雨荷载与风荷载的比值随高度增加而减少。针对大跨越输电塔线体系的静力极限承载能力,首先建立了三跨两塔的ANSYS有限元模型；其次依据现行规范,对该模型在四个风向角荷载作用下的静力极限承载能力进行分析,得到了最不利风向角以及各个风向角荷载作用下的破坏模式和极限承载能力。研究发现：塔线体系的破坏从塔底受压侧角柱开始；若考虑弯矩对轴力的影响,输电塔底层角柱发生应力屈服的荷载将减小；塔线体系的控制风向角为45度风向角,极限荷载为2.083倍的设计荷载。为了研究塔线体系的动力极限承载能力,本文计算了塔线体系在三种风荷载工况下的时程响应。研究发现：在10m高平均风速为50m/s的动力风荷载作用下,输电塔达到极限承载能力状态,底层受压角柱最先屈服,破坏时10m高度处脉动风速为55.1m/s。更多还原

【Abstract】 Large span transmission tower-line system can cross rivers and mountains. The four cross arms on the steel pipe large span transmission tower make the system transfer more power with less area. The tower is so high and the cross arms are so long that the ultimate carrying capacity of the system is different from the normal tower-line system.Wind load, wind drive rain load and ice load are the major environmental loads of the large span transmission tower-line system. One subject of the paper is wind-driven rain load of the tower; another subject of the paper is the ultimate carrying capacity of the tower-line system under wind load.In order to simulate the rain load, first, the fluctuating wind velocity inlet is needed. Based on harmonic wave superimposing method, the time history of fluctuating wind in open site was generated and used as the velocity inlet for flow field simulation. Second, the raindrops must be simulated properly, the fluctuating wind field and raindrops were respectively simulated by detached eddy model and discrete phase model. The rain load is solved at last. According to the impulse equivalence principle, rain load averaged over 0.25s time interval was calculated. The result shows that in all the load case, the biggest ration of rain load to wind load happens when the rain intensity is 709.2mm/h and the average wind velocity is 10m/s at the height of 18m. It’s also seen that the ration of the rain load to wind load decreases with height.The other subject of this paper is the ultimate carrying capacity of the tower-line system. The finite element model of a transmission tower-line system is established using ANSYS software. According to the standard of the state, the static ultimate carrying capacity of the system is calculated with four different wind attack angles. The static ultimate carrying capacity of the tower-line system is achieved and the break models of the tower-line system under the different wind attack angles are discussed. The result shows that bottom compressed columns yield first before all the other members. Considering the interrelationship between bending moment and axis stress, the yield load will be smaller. The ultimate carrying capacity of the system at the angle attack of 45 degree is smallest in all load case. The ultimate load is 2.083 times of the design load.The dynamic capacity of the system is studied at last. The dynamic response of the system is calculated under three load cases. The tower-line system breaks when the fluctuating wind velocity reaches 55.1m/s at the height of 10m. The bottom compressed columns are the first members exceed the yield stress.更多还原