猫头型输电塔在覆冰与风荷载下的动力稳定

利用增量动力分析法和弧长法有限元分析了猫头型输电塔的动力稳定,对比了输电塔静力与动力失稳前、后的受力特征,分析了覆冰厚度和风向角对输电塔动力失稳的影响。通过静力失稳与动力失稳塔顶侧移比相等原则得到了不同覆冰厚度及风向角下,输电塔动力失稳临界平均风速。结果表明:杆塔失稳主要由塔身底部主材屈服、斜材面外变形增大引起;随着覆冰厚度的增加,杆塔静力失稳与动力失稳的差别加大,杆塔在风力动载下的塔顶侧移显著增加,动力失稳临界平均分风速显著减小。输电塔在风荷载作用下的整体稳定性应考虑动力效应及覆冰条件的不利影响。

Study on dynamic stability of 220 kV cathead transmission tower under ice and wind load

The dynamic stability of cathead transmission towers is studied utilizing incremental dynamic analysis combining with arc length method in this paper. The pre-instability and post-instability behaviors of transmission tower under static loading and dynamic loading are investigated. The effects of ice thickness and wind attack angle on the dynamic instability of transmission tower are analyzed. The critical wind speeds of dynamic instability of transmission tower are captured by the principle of equal top drift ratio of tower. The analysis results indicate that the instability of transmission tower is triggered by the column yielding and brace buckling. The differences between static and dynamic instability become remarkable when the ice loading increases. Increasing the ice thickness increases the top drift ratio and decreases the critical wind speed of tower. The adverse effect of dynamic responses and ice load on the instability of transmission tower shall be taken into account in the design.