500kV输电杆塔结构抗风极限承载力试验研究

Experimental Study on Wind-resistant Ultimate Load-carrying Capacity of 500 kV Transmission Tower

为研究强风荷载作用下高压输电塔结构的极限抗风承载力和破坏机理,以风灾中遭到破坏的代表性500kV输电塔为原型,设计制作了典型塔段的缩尺结构模型,进行了等效风荷载作用下的静力加载破坏全过程试验。试验结果表明,结构破坏源于主材的弯扭失稳;在加载全过程中,交叉斜撑平面外变形呈现出不断增大的趋势。针对上述特征,基于原有模型,在其交叉斜撑节点位置增设了横隔面,并按原有加载规则进行了全过程加载,以考察这种改进之后结构体系的受力性能。研究发现,结构的破坏依然由主材屈曲引起,但其失稳模态由弯扭失稳趋向弯曲失稳;同时,交叉斜撑的面外变形得到了有效控制。对比结果显示:结构抗风极限承载力提高幅度达到22.1%。由于横隔面的存在,主材角钢失稳模态中扭转效应对临界承载力的不利影响被大幅降低,交叉斜撑面外变形对结构整体稳定的不利效应被显著抑制,结构的整体受力模式更趋合理,从而表明设置横隔面后的结构受力性能得到全面改善,其极限承载力和抗风性能得到了显著提升。

In order to study wind-resistant load-carrying capacity and failure mechanism of high-voltage transmission tower under severe wind storms,one subassemblage of a typical 500 kV transmission tower which was designed following the current code and suffered severe damage during wind storms was fabricated and statically tested under equivalent wind load.The test results showed that failure of structure was caused by torsional-flexural buckling of the main member.The out-of-plane deformation of the cross-bracings exhibited continuously increase.In view of these characteristics,one corresponding subassemblage which was added with horizontal diaphragm at the joints of cross bracings was tested under the same loading procedure.It was found that,for the improved structural system,instability of main member remained the primary failure pattern.But the buckling mode was transited from torsional-flexural buckling to flexural buckling.Meanwhile,the out-of-plane deformation in the joints of cross-bracings was reduced significantly.By comparison,it can be obtained that the ultimate wind-resistant load-carrying capacity is increased by 22.1%.Owing to the diaphragm,the unfavorable influence of torsion in the main member as well as the out-of-plane deformation of the cross bracings is inhibited.The mechanical performance of overall system is improved substantially.And it can be concluded that the structure with diaphragm behaves more brilliantly because its load carrying capacity and wind resistant performance are increased significantly.