考虑结构尺寸效应的台风场阵风因子特性分析

Characteristics of gust factors considering the structural size effect in typhoon wind field

为了克服现行固定时距阵风因子在进行结构抗风设计时潜在的不足,提出一种基于性能设计的阵风因子确定方法。首先,在极值理论所建立的阵风因子基础上,通过引入滑动平均滤波器与气动导纳函数等效的方法建立了考虑结构尺寸效应和平均风速的阵风时距确定方法;之后对常见的5种气动导纳函数进行分析得到了等效阵风时距计算公式;最后利用2006年到2008年间影响中国的三次台风过程实测数据,分别建立了A,B两类场地不同时距阵风因子曲线。研究结果表明:由Vickery通过实验测得气动导纳函数确定的等效阵风时距最大,由Newberry等实测得到的脉动风压相干函数经验式确定的等效阵风时距最小;综合五种气动导纳函数的计算结果,等效阵风时距可取为1.33倍的结构宽度与平均风速比值;随着场地粗糙度增加,阵风因子显著增大;实测台风场阵风因子大于规范给出相应场地类别推荐值。

In order to overcome the potential shortcomings of the fixed time scale gust factor used in wind-resistant design of buildings,aperformance-based design approach is proposed to determine the gust factor.First,a method to determine the gust duration based on the extreme value theory,which also considers the effects of the structural size and mean wind speed,is proposed by matching the moving average filter and aerodynamic admittance.After that,five distinct sources of aerodynamic admittance are examined to deduce the gust duration.Finally,based on the field measurements of 3typhoons from 2006 to 2008,the gust factor curves are given in category A and B.The results show that the gust duration determined by empirical aerodynamic admittance suggested by Vickery is the largest,while that determined by the coherence of wind velocity suggested by shiotani is the smallest and the average value is about 1.33 times the ratio of structural width to mean wind velocity.It also shows that the gust factor increases significantly with the increase of the roughness length,and the gust factor in typhoon wind fields are greater than the value in the corresponding terrain in〈Load code for the design of building structures〉of China.