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本文以某高压输电塔为研究对象,同时考虑了结构本身的随机性和地震作用的随机性,采用了非线性屈曲分析及动力响应分析对结构的抗震性能、地震反应进行了分析。在基于性能的分析框架下,通过蒙特卡罗数值模拟获得了输电塔的抗震能力曲线,并分析了其统计特性,计算得到结构的地震易损性曲线,为输电塔的抗震防灾规划提供风险评估的数据基础。 相似文献
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参照输电塔现行设计规范,首先,获得了风荷载作用下单塔结构的能力曲线,并依据结构构件的受力特征,以塔顶位移角为指标讨论了3种首次超越破坏的界限状态。其次,基于拉丁超立方抽样技术获得的结构等效静力计算样本,对界限值划分的合理性进行验证。最后,结合不确定分析样本的统计特性,计算塔架在最不利风向角下,不同顶点位移角限值的易损性曲线,并对比了采用动力可靠性分析获得的“三塔两线”体系计算结果。HCLPF(High Confidence, Low Probability of Failure)对应风速值表明,不同方法的计算结果较为接近,但单塔结构计算效率较高。 相似文献
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我国仍有大量采用容许应力法设计的在役77/78系列输电塔位于强风区,电网运行部门需要依据现行规范逐步进行加固改造。分别按照容许应力法和极限状态法给出了输电塔杆件安全系数表达式,对比分析了我国不同时期输电线路设计规范的风荷载和结构设计方法。以2021年发生风灾倒塔的两基77/78系列输电塔为研究对象,分别采用容许应力法和极限状态法计算了输电塔杆件应力、应力比和安全系数,并确定了强风下输电塔薄弱杆件位置。结果表明:SDJ 3—1979《架空送电线路设计技术规定》设计的输电塔安全系数明显低于SDGJ 94—90《架空送电线路杆塔结构设计技术规定》和DL/T 5154—2002《架空送电线路杆塔结构设计技术规定》,安全系数相差20%以上;且后两个规定设计的输电塔安全系数基本相当。 相似文献
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新国标GB 50009-2012《建筑结构荷载规范》中对风荷载计算部分做了较大修改,调整了风压高度变化系数和风振系数的计算,对输电塔设计影响较大。通过实例计算和对比分析,发现新规范较大幅度地提高了输电塔结构设计时风荷载的取值。 相似文献
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Many transmission towers have collapsed during severe gales and thunderstorms, and these failures have traditionally been attributed simply to wind loading. This study attempts to reveal the full failure mechanism of tower structures under strong wind excitation considering the rainfall effect. First, the calculation of rain load for a tower‐line system is provided. Then, an uncertainty analytical method for estimating the strength capacity and predicting the failure pattern of transmission towers induced by wind and rain loads is presented. Next, a real collapsed transmission line is considered to establish the finite element model, followed by the determination of the most vulnerable tower, which is then used to perform the uncertainty analysis. The results illustrate that the collapse basic wind speed considering the rainfall effect is smaller than the pure wind condition. In addition, the failure probability of the tower body is the largest, which is consistent with the deterministic method, whereas the most vulnerable tower began to fail from the tower leg in reality, indicating that the initial broken position of the transmission tower may not occur in the location with the largest probability and that the deterministic method is invalid in some cases. Finally, the influence of the wind attack angle and bundle number of transmission conductor is investigated. The most unfavorable wind attack angle is 90°, and the rainfall effect becomes increasingly significant with increases in the bundle number; this relationship should be given particular attention. 相似文献
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Fragility assessment of wood sheathing panels and roof-to-wall connections subjected to wind loading
Amira GILL Aikaterini S. GENIKOMSOU Georgios P. BALOMENOS 《Frontiers of Structural and Civil Engineering》2021,15(4):867
The performance of the wood-frame buildings after tornadoes has shown that the majority of the wind damage resulted from building envelope failure most typically due to the loss of the roof. To assess the performance and the reliability of low-rise wood-frame residential buildings with a focus on the roofs, fragility analysis can be used to estimate the probability of failure of a roof when constructed with specified nails and sheathing sizes. Thus, this paper examines the fragility of specific types of nails, roof-to-wall (RW) connection details, and sheathing sizes based on the damaged roofs that were previously assessed in the Dunrobin area in Ottawa (Ontario) that was hit with an Enhanced Fujita (EF3) tornado on September 21, 2018. The presented fragility analysis considers four scenarios, including different sheathing and nail sizes. Dead loads, wind loads, and resistance on the sheathing panels were compiled and analyzed to determine the failure of the examined roofs. The eight fragility models suggest that the safest roof sheathing (RS) is the 1.22 m × 1.22 m sheathing panel with 8 d nails, and the safest RW connections is achieved by using H2.5 hurricane clips. 相似文献
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Hurricane Wilma hit Yucatan Peninsula in 2005, causing substantial damage to local electrical transmission towers. Based on the failure characteristics observed on such towers, an analytical study is performed to reproduce such failures and assess their vulnerability. Two latticed transmission towers are analysed under the action of 14 different wind velocity patterns corresponding to several national and international wind design codes. Displacement-controlled pushover analyses are performed to reproduce impending failure mechanism for considered wind patterns, and associated gradient wind speed is computed. Results illustrate that consistent cyclonic wind speed patterns lead to better estimates of failure mechanism and gradient wind values than traditional non-cyclonic patterns. 相似文献
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风荷载作用下输电塔结构体系可靠度分析 总被引:2,自引:2,他引:0
用荷载增量法结合有限元分析技术,通过枚举列出输电塔体系的主要失效路径,提出了蒙特卡洛概率方法,并通过Matlab软件计算出各输电塔体系的失效概率,最后以一大型输电塔进行了可靠度计算。 相似文献
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基于地震荷载的作用,应用大型有限元软件FINAL,研究不同结构参数的风力发电塔在地震荷载作用下的地震响应,以及比较它们之间的差异,进而得出改变风力发电塔的结构参数对于地震响应的影响规律.以二维风力发电塔模型为例,建立4个不同参数的模型,首先进行模态分析,计算出每个模型的固有频率,通过比较固有频率得出结论,并对其进行比较分析.然后对4个模型施加1993年北海道西南海面桥地震波形,分析比较它们在此地震波形作用下的地震响应值,进而得出不同的结构参数对地震响应的影响规律. 相似文献
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覆冰荷载下输电铁塔体系可靠度研究 总被引:1,自引:0,他引:1
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。 相似文献
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采用谐波叠加法,模拟了输电塔塔顶脉动风速时程曲线及风荷载时程.介绍了LQR控制算法的原理,利用MATLAB语言编制了LQR控制算法的程序,并对一输电塔模型结构在风荷载作用下的控制效果进行分析,结果表明,LQR控制方法可以有效地减小输电塔的风振响应,说明LQR控制方法是一种比较理想的减震方法. 相似文献