钢管塔K节点的加劲肋布置和极限承载力研究

 特高压输电线路酒杯型钢管塔K节点是受力最复杂的节点,其主管与支管的夹角θ往往小于30°,不能满足国内现行的K节点承载力计算方法规定的θ≥30°的要求.为了解决该问题,本文应用通用有限元软件ANSYS进行数值模拟仿真,验证现有设计验算方法的适用性.针对钢管塔相贯焊连接的K节点设计了3种新型的加劲肋,并对其受力分布和极限承载能力进行分析对比.研究结果表明,θ超出现行规范的规定时,规范对个别工况不适用;新设计的加劲肋布置方案,能显著改善节点危险部位的应力分布,消除应力集中,降低最大应力.在目前没有合适计算公式的情况下,应继续使用现行规范,并采用本文设计的节点加劲肋布置形式增大结构的承载力和安全性.

Rib Stiffener Distribution and Ultimate Strength of Steel Tubular Tower's K-joint

The K-joints of the cup type steel tubular tower in Ultra High Voltage (UHV) transmission lines are nuder the most complex loads. The angle θ between K-joint's chord and brace is usually less than 30°, while the method of calculating K-joint's ultimate strength in Chinese current "Code for design of steel structures" GB 50017—2003 requires that, θ must be no less than 30°. To deal with this problem, a general finite element software-ANSYS is used for its numerical simulation. The applicability of the current designing and calculating method is checked by the result of the simulation. 3 kinds of new rib stiffeners for directly-welded K-joint of steel tubular tower are designed. And the stress distribution and the ultimate strength of the new stiffeners are compared. It is shown that, if θ goes beyond the limit of the criterion, the calculating method in the code would fail for some engineering cases. With the new-designed rib stiffener, the stress distribution in K joint's dangerous area is improved obviously with the stress concentration eliminated and the maximum stress lowered. It is suggested that, the current code should be kept in use, because there is not a suitable alternative at the present. And the designed rib stiffeners should be adopted to increase the ultimate strength and security of the structure.