角度风作用下输电塔线体系风荷载及风振响应计算方法研究

The transmission line system is the important life-line engineering which is sensitive to fluctuating wind loads. For the large scale of the span length, the transmission line system is usually subjected to skew incident winds. Many on-site monitoring and wind tunnel experiments indicates that the crucial wind condition may occur at the direction about 45 or 60 degrees to the span orientation. However, many researches mainly focus on the wind direction normal to the line. The codal specifications, derived from triangular decomposition, are not substantially supported by experimental proof. With regards to the lack of researches concerning such issue, this project aims to establish an evaluation approach for the dynamic response of transmission line system under skew incident winds through theoretical, numerical and wind-tunnel experimental means. Firstly the shielding effect of sub-structures of the lattice tower and bundled conductor will be studied to provide a more accurate three-dimensional wind load model for dynamic analyses under skew winds. Secondly the dynamic response of the conductor will be systematically investigated and the calculation method of the dynamic tension under skew winds is supposed to be established. Then the wind-structure interaction will be investigated by identification of the aerodynamic damping of the transmission line system in different conditions. Finally, based on the foregoing researches, the method to analyze the dynamic response of transmission line system under skew incident winds will be proposed and verified. The result of this project is supposed to provide a more comprehensive and elaborate way to estimate the dynamic response of transmission line system for crucial wind conditions. And it is of great significance to comprehensive applications such as fatigue analyses and life-time evaluations.

输电塔线体系是重要的生命线工程，对脉动风敏感。由于导线跨度大，角度风对塔线体系具有很大影响，实测及风洞试验表明，来流风与跨度方向成45~60度角时是风振响应的控制工况。然而目前大量研究仅针对风向垂直于导线的情况，我国规范基于三角分解原理计算角度风下结构风振响应的方法缺乏试验依据。鉴于相关研究较不成熟，本申请书目的是建立角度风下塔线体系动力响应分析方法。通过理论、数值模拟和风洞试验相结合的手段，本申请书首先着眼于输电塔子结构和分裂导线的遮挡效应以建立更为精细的三维风荷载模型，其次系统地研究导线在角度风下的动力响应并建立导线动力荷载的分析方法，第三通过对塔线体系气动阻尼的识别以研究流固耦合作用的影响，最后建立并验证角度风下塔线体系风振响应分析方法。本项目的成果将为塔线体系在关键工况下的动力响应评估提供更全面和精细的分析手段，并在其他相关研究比如疲劳分析和生命周期研究上都具有广泛的应用前景。

输电线路实际所受风荷载的作用方向与线路走向的夹角通常不等于90°，而线路的设计又受角度风工况控制，现行输电线路设计规范中角度风下的风荷载计算采用经验的分配系数，取值合理性有待研究。本项目通过风洞试验、CFD模拟和理论分析研究了角度风作用下输电线和输电塔风振响应和风荷载计算方法。完成了角度风下分裂导线高频测力天平试验、角度风下角钢输电塔和钢管输电塔典型子结构高频测力天平试验、角度风下输电塔线体系气弹模型风振响应风洞试验。对数百个分裂导线模型进行了CFD模拟，研究了气动力系数随导线直径、分裂数、环向角、风向角等参数变化规律以及导线尾流场特点和屏蔽效应机理，建立了角度风下考虑屏蔽效应的分裂导线气动力系数计算方法。.基于风洞试验和CFD模拟分析，研究了不同风向角下角钢和钢管塔头横担、塔身及塔腿节段阻力系数的变化规律，得到了角钢和钢管塔头横担、塔身及塔腿节段的角度风系数。研究了常用风向角下单根角钢构件的阻力系数变化规律以及不同杆件间距比下背风面角钢的阻力系数及背风面杆件遮挡效应。研究了串列、并列和错置状态下的等直径双圆管、等直径四圆管和等直径三圆管在不同环向角和不同间距比下的气动力特性。.研究了塔线体系耦合振动的特点及能量传递规律以及长横担输电塔风振过程中的扭转效应。揭示了不同风向角下单塔及塔线体系风振响应机理，得到了单塔及塔线体系最不利风向角；提出了输电塔气动阻尼计算公式。提出了塔架、导线和拉线风振系数计算方法，给出了计算公式并编制相应表格。建立了适用于任意档距、高差、耐张串长度和气象条件的连续档导线张力弧垂通用计算方法。提出了适用于大跨越输电塔考虑高阶振型进行频谱分析的判别式。研究工作为工程设计应用提供了参考。.基于准定常理论，研究了角度风作用下塔架的体轴向的风荷载计算方法，建立了角度风作用下导线的三维风荷载计算模型，建立了塔线体系三维风荷载计算方法。