风荷载作用下输电塔极限承载力和失效模式计算模型

摘要

针对现有输电塔极限承载力和失效模式研究未考虑计算模型影响的问题,剖析了空间桁架、空间刚架和空间梁桁组合3种常用计算模型的力学基础和模拟方法;以110 kV鼓形直线输电铁塔为例,对比研究了0°,45°,60°,90°四种风向工况下3种计算模型的弹性响应,同时对比分析了最不利工况下各计算模型极限承载力和失效模式的计算结果,揭示了不同计算模型对结构极限承载力和失效模式的影响规律.结果表明:空间刚架和空间梁桁组合模型较桁架模型能给出偏安全的弹性响应结果;该类输电塔最不利风荷载工况下的极限活荷载乘子约为2.00,空间梁桁组合模型能反映铁塔结构的延性破坏性质,给出偏安全的极限承载力计算结果;该类输电塔高承载构件主要集中在塔腿主材,空间刚架和空间梁桁组合模型都能较准确识别出高承载构件;建议采用空间梁桁组合模型进行输电塔极限承载力和失效模式的分析.%In order to solve the problem of not taking account of the influence of calculation models on ultimate bearing capacities and failure modes of the existing transmission towers,the fundamental mechanical principles and simulation methods of the three commonly used models, including space truss,space rigid frame and space beam-truss,were illustrated.Taking a 110 kV drum type linear transmission tower as an example,the elastic responses of 3 calculation models under for 0°,45°,60°,90° wind load were compared.The calculation results of the ultimate bearing capacity and failure mode of each calculation model under the most unfavorable conditions w ere compared and analyzed.T he influences of different calculation models on the ultimate bearing capacity and failure modes of structure were revealed.The results show that the rigid frame and beam-truss model can give safe elastic response results compared with the truss model.The limit live load multiplier of this type of transmission tower is about 2.00 under the worst wind load condition.The beam-truss composite model can reflect the ductility failure properties of the tower structure and give safer calculated results of ultimate bearing capacity.The bearing components of this kind of transmission tower mainly concentrate in the tower leg materials.The rigid frame and beam-truss model can accurately identify high load bearing member.The space beam-truss composite model is proposed to be used for analyses of ultimate bearing capacity and failure mode of the transmission tow er.