拉线门塔在下击暴流作用下的响应分析

Analysis on Downburst Induced Response of Guyed Portal Tower

以某220kV输电线路拉线门塔为工程背景,通过时程响应分析对比研究了拉线门塔在下击暴流与常规B类风场作用下的响应特性.建立了拉线门塔-输电线体系空间有限元模型并进行了动力特性分析,通过风洞试验测试了拉线门塔刚性模型和双分裂导线模型的体型系数,模拟了规范B类风场和下击暴流风场的脉动风荷载时程,采用Newmark-β法分析了拉线门塔在两种风场脉动荷载作用下的响应,并与规范设计荷载等效静力作用下的效应进行了比较.结果表明:拉线门塔在下击暴流作用下,立柱峰值压应力达到600MPa,是常规B类风场作用下的4.6倍;拉线极值拉应力达到1 300 MPa以上,是常规B类风场作用下的2.5倍;且拉线门塔位移响应以导线频率占主要成分的低频响应为主,导线荷载对拉线门塔位移响应影响显著而对其加速度响应影响甚微.比较研究表明,中国规范缺乏下击暴流风荷载的设计条文,但是对杆塔进行常规B类风场作用下的设计取值是合理的,而美国ASCE荷载导则的计算方法会低估下击暴流对拉线门塔的破坏作用.

Taking the guyed portal tower of a 220 kV transmission line as the background,comparative studies on the response characteristics of the guyed portal tower under a downburst and terrain B wind field were carried out by the time history response analysis.3-D finite element model of guyed portal tower-transmission line system was established,and the dynamic characteristics analysis was performed.The static force coefficients of the rigid guyed portal tower model and double-model were obtained by wind tunnel tests.Based on the numerically simulated fluctuating wind load induced by the downburst field and Chinese code defined terrain B wind field,the responses tower under the fluctuating wind loads were analyzed through the Newmark-^method,which was comparedwith the results based on the codes defined equivalent static loads.The results show compressive stress of the tower elements and the maximum tensile stress of the guy wires induced by the downburst are 600 MPa and 1 300 MPa,which are 4.6 times and 2.5 times to the corresponding by conventional terrain B wind field,respectively.In addition,low frequencyAbstract:Taking the guyed portal tower of a 220 kV transmission line as the background,comparative studies on the response characteristics of the guyed portal tower under a downburst and terrain B wind field were carried out by the time history response analysis.3-D finite element model of guyed portal tower-transmission line system was established,and the dynamic characteristics analysis was performed.The static force coefficients of the rigid guyed portal tower model and double-model were obtained by wind tunnel tests.Based on the numerically simulated fluctuating wind load induced by the downburst field and Chinese code defined terrain B wind field,the responses tower under the fluctuating wind loads were analyzed through the Newmark-^method,which was comparedwith the results based on the codes defined equivalent static loads.The results show compressive stress of the tower elements and the maximum tensile stress of the guy wires induced by the downburst are 600 MPa and 1 300 MPa,which are 4.6 times and 2.5 times to the corresponding by conventional terrain B wind field,respectively.In addition,low frequency