覆冰荷载下输电铁塔体系可靠度研究  

System reliability of a transmission tower under ice load

作　　者：熊铁华[1] 侯建国[1] 安旭文[1] 李峰[2] 

机构地区：[1]武汉大学,湖北武汉430072 [2]中国电力科学研究院,北京100055

出　　处：《土木工程学报》2010年第10期8-13,共6页China Civil Engineering Journal

摘　　要：研究在覆冰荷载作用下,输电铁塔主要失效模式及其体系可靠度。建立覆冰荷载作用下寻找输电铁塔主要失效模式的方法,该方法以覆冰厚度为控制量,可以方便地获得铁塔的主要失效模式及相应的极限覆冰厚度。利用基于响应面的随机有限元法来获得各失效模式上各个单元的极限状态方程,然后用逐步等效线性化法得到各失效模式的等效线性化极限状态方程。所有的失效模式组成一个串联系统,计算各失效模式间的相关系数,最后由Ditlevsen界限法计算输电铁塔体系可靠度。分析在2008年初的冰雪天气里发生倒塌的我国南方某220kV输电铁塔的主要失效模式及其体系可靠度。通过计算指出由于不平衡张力的存在,使输电铁塔的极限覆冰厚度接近于它的设计覆冰厚度;同时指出:如果借鉴构件的目标可靠度指标的话,既有输电铁塔在设计覆冰条件下,体系可靠度指标不能满足要求。The dominant failure modes and system reliability of a transmission tower under ice load were analyzed.A method considering ice thickness was introduced to generate the dominant failure modes and the limit ice thicknesses of a transmission tower.The system reliability was evaluated through the following steps： ① Stochastic FEM based on response surface was proposed to obtain a set of limit state functions of failure elements,and then an equivalent linear margin for these limit state functions was introduced;② As all failure modes formed a series system,the correlation coefficients between failure modes were evaluated;③ The transmission tower system reliability was computed using the Ditlevsen bounds method.A 220kV transmission tower in south China,which was crashed in 2008 due to ice load,was analyzed to obtain the dominant failure modes and system reliability.The numerical example indicated that the limit ice thickness of the tower was close to the design ice thickness because of unbalanced tension,and that the system reliability index was too small to satisfy the targeted value.

关 键 词：失效模式 体系可靠度 输电铁塔 覆冰荷载 极限荷载 响应面法 

分 类 号：TB114.3[理学—概率论与数理统计]