盐渍土环境下考虑耐久性损伤的输电塔风振时程分析

Time history analysis of transmission tower under wind vibration considering durability damage in saline soil environment

长期服役于盐渍土环境下的输电塔耐久性损伤较为严重,当其材料力学性能退化到一定程度时,在强风作用下,输电塔可能会发生破坏,危害线路的安全运行。基于±800kV天中线特高压直流输电工程直线塔,考虑基础钢筋锈蚀、基础混凝土侵蚀、输电塔杆塔钢材锈蚀以及基础箍筋的约束效应,在ABAQUS有限元软件中建立塔-线-基础耦合模型,研究不同风攻角和材料耐久性损伤对塔身动力响应的影响。结果表明:90°风攻角下塔身顺风向位移最大,为最不利风向基本工况;90°风攻角下输电塔塔顶顺风向位移响应贡献主要以背景分量为主,但共振分量也有一定贡献,主要以输电塔1阶振型频率为主,且随着服役时间的增加,振型频率逐渐降低,相应响应的贡献程度逐渐提高;相同风荷载作用下,随着服役时间的增加,塔身位移逐渐增大,相同服役时间下,随着塔身高度的增加,塔身位移响应峰值增长速度变快,结构振动更加明显,材料耐久性损伤对输电塔的位移响应影响较大。

The durability damage of transmission towers that have been in service for a long time in saline soil environment is serious.When the mechanical properties of their materials degrade to a certain extent,the transmission towers may be damaged under the action of strong wind,which will endanger the safe operation of the line.Based on the linear tower of±800 kV Tianzhong line ultra high voltage direct current transmission project,the foundation reinforcement corrosion,foundation concrete corrosion,steel corrosion of transmission tower and the constraint effects of foundation stirrup were considered.The tower-line-foundation coupling model was established in ABAQUS finite element software to study the effects of different wind attack angles and material durability damage on the dynamic response of the tower.The results show that the downwind displacement of the tower is the largest under the wind attack angle of 90°,which is the most unfavorable wind condition.At 90°wind attack angle,the contribution of the downwind displacement response from the top of the transmission tower is mainly the background component,but the resonance component also has a certain contribution,which is mainly the first mode frequency of the transmission tower,with the increase of service time,the mode frequency of the transmission tower gradually decreases,and the contribution degree of the corresponding response gradually increases.Under the same wind load,with the increase of service time,the tower displacement gradually increases.In the same service time,with the increase of tower height,the peak value of the tower displacement response increases faster,and the structural vibration becomes more obvious.The durability damage of materials has a great influence on the displacement response of the transmission tower.