特高压长悬臂输电塔结构风振扭转响应

来源期刊:中南大学学报(自然科学版)2020年第4期

论文作者:蔡建国 张骞 叶震 余亮 冯健

文章页码:1108 - 1116

关键词:特高压;长悬臂输电塔;风振响应;扭转效应;风向角;横担长度

Key words:ultra high voltage(UHV); long cantilever transmission tower; wind-induced response; torsional effect; angle of direction wind; length of the cross arm

摘    要:在分析±1 100 kV特高压长悬臂输电塔的风振扭转响应机制的基础上,通过有限元动力时程计算考察扭转效应对结构内力的影响。首先,计算特高压长悬臂输电塔结构横担部位的风振系数;其次,根据横担的位移时程结果明确输电塔结构的风振扭转效应;最后,定义等效扭转风振系数,计算脉动风作用下的附加扭转荷载,分析风向角和长悬臂输电塔横担总长度对结构扭转效应的影响。研究结果表明:在风荷载动力时程的作用下,长悬臂输电塔结构会产生约0.01 rad整体扭转,考虑附加扭转工况可以提高输电塔主材和斜材的设计可靠度,提高程度从高到低依次为塔身斜材、横担斜材、横担主材和塔身主材;应力包络程度从74.4%提升到93.6%,且对所有主材和斜材,考虑扭转荷载的静力计算结果对动力时程计算结果的包络程度均在90%以上;不同风向角时,输电塔结构的扭转效应和横担风荷载Y方向的分配系数呈正线性关系,其中0°风对应的等效扭转风振系数最大,达到0.75,而90°风对应的等效扭转风振系数为0。随着输电塔结构的横担总长度减小,结构的扭转效应也减小,0°风对应等效扭转风振系数先减小后稳定在0.55附近,且拐点与结构的扭转振型的阶次有关。当扭转阵型为低阶阵型时,长悬臂输电塔结构的风振扭转效应明显。

Abstract: The dynamic time history analysis of ±1 100 ultra high voltage(UHV) long cantilever transmission tower structure was carried out to investigate the effect of torsional response on internal force of members after the mechanism analysis of wind-induced torsional response. Firstly, the wind vibration coefficient of arm cross of the UHV long cantilever transmission tower structure was calculated. Then, the torsional effect can be determined by displacement time history results of the arm cross. Lastly, the additional torsional load under the consideration of the pulsating wind was given by defining the equivalent torsional wind vibration coefficient, and the influence of wind direction and total length of the cross arm on the structural torsion effect was discussed. The results show that the global torsion is 0.01 rad for the long cantilever transmission tower subjected to wind loads. The reliability of main member and the oblique member in the tower can be improved by considering the additional torsional wind load condition, and the improvement degrees are sorted by oblique members in the tower body, oblique members in the cross-arm, main members in the cross-arm and main members in the tower body from highest to lowest. Noticeably, there is a most obvious increase in the design reliability of the bottom oblique members from 74.4% to 93.6%. For all the main and oblique members, the stress envelops are above 90%, which can be given from the comparison between the static results considering torsion loads and the results of the dynamic time history method. The torsion effect of the transmission tower structure in different wind directions is positively linearly related to the load distribution coefficient of Y direction. In addition, the equivalent torsional wind vibration coefficient for 0° wind is the largest at 0.75, while that for 90° wind is 0. With the decrease of arm cross length, the torsional effect drops, and the equivalent torsional wind vibration coefficient decreases gradually and then levels off at approximately 0.55. The inflection point is related to the order of the torsional vibration mode of the transmission tower structure. The wind-induced torsional effect becomes obvious when there is a low-order torsional vibration mode.

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