台风风场参数对输电杆塔力学特性的影响

Study on the Influence of Typhoon Wind Parameters on Mechanical Characteristics of Transmission Tower

分析输电杆塔风荷载计算公式可知,台风风场的平均风速、风剖面指数与湍流强度是影响杆塔风荷载的主要参数,而台风在整个行进过程中,这些风场参数不断变化并共同影响输电杆塔的风荷载。为探索台风行进过程中杆塔受力变化规律,首先选取了台风卡努行进过程中5个不同时刻的风场,开展了对应的杆塔受力分析。分析结果显示,杆塔应力比与平均风速的变化规律趋于一致。而后在设计风速一致的前提下,以某大跨越杆塔为工程背景,开展了台风与常规风两类风场作用下杆塔风荷载和受力对比计算。参数分析显示,台风与常规风风剖面指数的差异对杆塔风荷载和受力影响较为显著,最有可能引发倒塔事故。最后通过分析塔材应力比沿塔身分布规律,找到了台风荷载作用下杆塔的薄弱部位,提出了补强措施,还选取了其他类型常用杆塔进行试算,对这一补强措施的适用性加以验证。

According to the wind load equation of transmission tower, the parameters of the mean wind speed, wind profile coefficient and turbulence intensity are believed to be the main influencing factors of wind load. Moreover, all above-said parameters, as well as the wind load and the static response, vary during the traveling of typhoon. Therefore, in order to identify the most influential factors of these three wind parameters, the wind fields at five different time interval of the typhoon Khanun are picked out firstly. Through the mechanical analysis, it can be found that the mean wind speed has significant influence on the mechanical characteristics of transmission tower. Then, under the condition of the same wind speed, a large-span transmission tower is chosen for case study. Through comparison of the wind load and mechanical characteristics, it is demonstrated that the wind profile coefficient may have greater influence and may induce tower collapse. Finally, by analyzing the member bar stress ratio distribution along the tower height, the weak point of transmission tower under typhoon is identified. Some reinforcing measures are proposed in this paper, which are proved to be effective by another widely used tower type.