输电塔倒塌失效模式和主材角钢加固方法研究

Study on failure modes and retrofitting method for leg members of transmission tower

为了提高服役期输电塔抵御极端气象灾害的能力,保证输电线路的安全稳定运行,以220 kV典型输电塔为例,利用有限元方法对其进行了抗风极限承载力研究,分析强风作用下输电塔的倒塌机理和破坏模式。针对输电塔的失效模式,提出了一种输电塔无损加固方案,通过建立不同长细比主材角钢构件的有限元模型,对加固前后主材的轴压承载力进行了数值模拟,并对输电塔整塔薄弱部位主材进行了加固设计,研究了加固后输电塔的极限抗风承载力。研究表明,加固后的主材角钢承载力大幅提升,最高可达37.2%。输电塔的薄弱部位主材加固后的局部刚度提升较大,输电塔的塔顶位移和最大应力与未加固前相比均显著降低,铁塔极限承载力大幅提升,输电塔的设计重要性系数由1.15提升至1.35,提出的加固方法可为同类型输电塔的抗风加固设计提供重要参考。

In order to improve the ability of transmission towers to resist extreme meteorological disasters in service and ensure the safe and stable operation of transmission lines,a typical 220 kV transmission tower is taken as an example,and the finite element method is used to study its wind resistance ultimate load bearing capacity and analyze the collapse mechanism and damage mode of transmission towers under strong wind.In view of the failure mode of the transmission tower,a non-destructive reinforcement scheme is proposed.By establishing finite element models of angle steel members with different length to slenderness ratios of the main material,the axial compression load capacity of the main material before and after reinforcement is numerically simulated,also the reinforcement design is carried out for the main material of the weak part of the transmission tower,and the ultimate wind bearing capacity of the reinforced transmission tower is studied.The results show that the reinforced main material angle bearing capacity is greatly increased,up to 37.2%.The local stiffness of the weak parts of the transmission tower is improved,the top displacement and the maximum stress of the tower are significantly reduced compared with those before reinforcement,the ultimate bearing capacity of the tower is greatly increased,and the design importance factor of the transmission tower is increased from 1.15 to 1.35.The proposed reinforcement method can provide an important reference for the wind resistance reinforcement design of the same type of transmission tower.