山区长短腿输电塔的动力失稳研究

Dynamic Instability of Transmission Tower with Unequal Legs in Mountainous Area

对山地丘陵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进行研究。采用B-R准则和动态增量法(IDA)并结合位移等值准则,考虑不同风载的作用,并模拟山区脉动风载对输电塔进行非线性屈曲分析和时程分析。研究表明,塔靠近山顶侧发生受压破坏而山谷侧是受拉破坏,破坏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中将风等效为静力荷载的方法是偏于不安全的。

This research focuses on the wind-induced dynamic characteristics of 5B-ZBC4 transmission tower with unequal legs,the commonly-used type of transmission towers in B-Class mountainous area.The effects of different wind loads were analyzed by use of B-R criterion and dynamic incremental method（IDA） combined with displacement equivalence criteria.In addition,the nonlinear buckling analysis and time-history analysis were both conducted for the transmission tower by simulating the fluctuating wind in mountainous area.As research indicated,the tower compression failures occurred on the hill-top side,and tensile failures on the valley side;damage gradually extended leg-to-head,eventually leading to the tower collapse.Therefore,it tends to be unsafe that the present wind-resistance design specification for mountainous transmission towers defines wind as the equivalent of static load.