山区长短腿输电塔的动力失稳分析

Dynamic Instability of Transmission Tower with Unequal Legs in Mountain Area

针对山区长短腿输电塔在静风和脉动风作用下动力失稳问题,为寻求输电塔失稳极限风速和破坏发生路径,研究了山地丘陵B类地貌常用5B-ZBC4型长短腿输电塔在风载作用下的动力特性,采用B-R准则和动态增量法(IDA)并结合位移等值准则,考虑了不同的风载作用,模拟了山区脉动风载对输电塔进行非线性屈曲分析和时程分析。结果表明,输电塔靠近山顶侧发生受压破坏、山谷侧为受拉破坏,且从塔腿开始逐渐发展到塔身,最终导致倒塔事故;现行山地丘陵输电塔的抗风设计规范将风等效为静力荷载的方法偏于不安全。

Aiming at the dynamic instability of transmission tower with unequal legs in mountain area under the action of wind load, the common 5B-ZBC4 transmission tower with unequal legs in B-type geomorphy of hilly land is studied to seek the ultimate wind speed and damage path. According to B-R criterion and displacement equal criterion with combination of incremental dynamic act （IDA）, considering the different fluctuating wind-load in mountain areas, the method of numerical simulation is used to analyze the unequal legs tower in the nonlinear buckling and time-history characteristic. The results show that the tower near the top of the hill appears compression failure and the tensile failure appears in the mountain valley; the damage gradually develops into the tower body from the tower leg and eventually it leads to the tower eollapse;in the current mountainous transmission towers wind-resistant design specification, the wind equivalent of the static load is unsafe.