基于HFFB试验高耸结构风荷载谱高度修正系数及风振分析

Height correction factor of the wind load spectrum of towering structures based on HFFB tests and wind vibration analysis

分段估计法作为一种重要的非线性振型结构高频天平(high-frequency force balance,HFFB)试验模态力计算方法,可以对结构脉动风荷载的空间分布进行估计。该文章抛弃了分段估计法中无量纲风荷载谱沿高度不变的假定,提出了一种可以考虑荷载谱沿高度变化的方法。以Kaimal脉动风谱为例提出并推导了无量纲风荷载谱沿高度变化的修正系数,并以某真型输电塔架为算例,结合HFFB试验,分析了修正系数对结构响应计算的影响。研究结果表明,修正前后位移响应的背景分量计算值差异很小,但共振分量差别明显,偏差幅度达25%。对柔度较大的高耸结构,其共振分量在总响应中占比较高,需考虑荷载谱沿高度的变化;对于沿高度减小或增大的风速谱而言,现有荷载谱沿高度不变的分段估计法将高估或低估结构的位移响应。本文方法具有更高精度和更广的适用性。

The segmental estimation method is an important modal force calculation method for high frequency force balance(HFFB)tests of nonlinear mode-shape structures.It allows to carry out the estimation of the spatial distribution of fluctuating wind load on structures.The assumption that the dimensionless wind load spectrum is constant along the height in the segmental estimation method was discarded,while proposing a method that can consider the variation of the load spectrum along the height.The Kaimal fluctuating wind spectrum was taken as an example to propose and derive a correction factor for considering the variation of dimensionless wind load spectrum along the height.A practical transmission tower was used as a calculation example,and the influence of the correction factor on the structural response calculation was analyzed,combining with the HFFB tests.The results show that the difference between the calculated values of the displacement response’s background component before and after the correction is small,but the difference between those of the resonance component is obvious,with a deviation of 25%.For towering structures with greater flexibility,where to carry out the resonance component is higher in the total response,the variation of the load spectrum along the height needs to be considered.For the wind speed spectrum decreasing or increasing along the height,the existing segmental estimation method for the load spectrum constant along the height will overestimate or underestimate the displacement response of the structure.The method proposed has higher accuracy and wider applicability.