中文摘要：

下击暴流为雷暴天气中强下沉气流猛烈冲击地面后形成并沿地面传播的近地面短时强风,其风场特征同传统的大气边界层近地风显著不同。近年来下击暴流作用下输电线-塔结构的倒塌破坏事故层出不穷。根据美国、澳大利亚和南非等国的调查,80%以上的输电线-塔的风致倒塌事故主要为下击暴流所引起。而我国对此却少有研究。据此,本文简要介绍了下击暴流在输电线-塔抗风研究中的重要性,并从尺度特征、风速特征、随机特征和压力特征四个方面对下击暴流的基本特征进行了综述。其次,阐述了下击暴流对输电线-塔结构的灾害作用和下击暴流作用下输电线-塔的破坏特征。最后,论述了下击暴流对输电线-塔结构抗风设计的影响。指出了将雷暴强风,尤其是发生频度高、破坏性强的下击暴流纳入到风荷载规范,是非常重要而迫切的工作。

英文摘要：

Downburst is an outburst strong wind on or near the ground, and its wind field characteristics are significantly different from boundary layer winds. It is reported that many transmission towers collapsed under downburst in recent years. Investigations of transmission towers failed in America, Australia and South Africa have reported that more than 80% of all the weather related line failures were the results from downbursts that are associated with the occurrence of thunderstorms. Hereby, the importance of downbursts to transmission towers was introduced and a comprehensive survey on flow characteristics of downbursts from four respects,i.e. scale features, velocity features, random features and pressure features was made. Then, the disasters of downbursts on transmission towers and downburst-induced transmission tower’s damage characteristics were discussed. Finally, the importance of downburst-resistance to transmission towers was described. It was pointed that it is very important and urgent task to take the downburst into wind loading codes.