长短腿耐张输电铁塔的静力及自振特性分析

Static and Self-vibration Characteristic Analysis of Strain Towers with Unequal Legs

采用MATLAB及SAP软件,对长短腿耐张输电铁塔与等长腿耐张输电铁塔在多工况荷载下的静力及自振特性进行了比较分析。静力计算结果表明:在各工况荷载下,长短腿塔的底部塔柱轴力较等长腿塔均有增大,但底部斜杆轴力变化有增有减且变化幅度大,无横隔约束时长短腿塔塔身下半部斜杆更加敏感,上部杆件轴力受长短腿的影响很小;一般情况(除"短腿一侧出现断线或张力不平衡的情况"外)下顺侧向荷载方向位移较等长腿塔有所减小,但垂直侧向荷载方向位移增大显著。自振特性分析表明,长短腿增强了铁塔高阶振型的平扭耦联效应,长短腿产生的结构支座高差方向对结构纵向及横向的前几阶振型有很大影响。

Compared with normal transmission towers and based on finite element analysis with MATLAB and SAP, the static and self-vibration characteristics of strain towers with unequal legs under different loads are analyzed in this paper. Static calculation results show that as compared with normal towers under different loads, the axial forces at the bottom posts of unequal-leg towers are greater, while the axial forces at the bottom diagonals undergo considerable increase and decrease; the diagonals at the lower tower body are more sensitive without the restriction of cross baffles, while the unequal legs have little influence on the axial forces at the upper members; the displacement along lateral load reduces under general situations （except for those with conductor breakage or unbalanced tension on the short-leg side）, but the vertical displacement increases notably. The self-vibration characteristic analysis indicates that the unequal legs intensify the lateral torsional coupled effect of steel-tower high-order vibration, and the height difference direction at the base has great effect on the structural longitudinal and lateral vibration of the first few orders.