横隔面在高压输电塔抗风设计中的作用分析

Effects of Diaphragm on Wind Resistant Design of Power Transmission Towers

高压输电线路是一种风敏感结构体系。强风暴是对输电线路威胁最大的一种自然灾害,因强风暴而导致的高压输电线路和输电塔破坏事故时有发生。为了保持结构的整体性能以及分配剪力和抗扭,输电塔的设计中都要设置一定间距的横隔面。横隔面设置位置和数量的多少影响到结构的整体抗风性能。以500 kV同塔双回路直线自立塔为例,研究了设置不同横隔面时结构的模态以及抗风内力与变形。按现规程的设计结构的第3振型已出现严重的局部振动,拟静力分析结果也显示无横隔面的斜撑出现了很大的平面外变形;增设横隔面以后,前几阶振型未发现局部振型,且斜撑的平面外变形也大大地降低。研究表明目前高压输电塔抗风设计规范中的横隔面设置数量和方法有待改进。

High-voltage transmission line system is sensitive to wind loads. Severe storms are the biggest threats to the system among all the naturalhazards. Many transmission llne and tower failures worldwide are attributed to severe storms. In order to maintain the global stability and to distribute shear and torsional forces, diaphragms with some intervals are required in designing transmission towers. Numbers and locations of diaphragms have significant effects on the global wind resistance of structures. Based on the design of a 500 kV double circuit tangent suspension tower, this paper analyzes the modal shapes and internal stresses and deformations of towers with different diaphragrn arrangement subjected to wind loads. Severe local vibration appears in the third mode shape of the tower, which is designed strictly following the current regulations. Static analysis alsoshows that diagonal braces in the tower body part without corresponding diaphragm have very large out-of-plane deformation. After adding diaphragms, the local vibration is suppressed in the firstseveral modes and the out-of-plane deformation of the diagonal braces is remarkably decreased. The results show that the current design code for transmission tower needs to be upgraded to consider adding more diaphragms at critical locations to ensure the global stability.