大跨索穹顶屋盖结构风洞试验及敏感风速研究

Wind tunnel test and sensitive wind speed study of large-span cable dome roof structure

大跨索穹顶屋盖结构频率密集,其风振动力响应复杂,不同风速下脉动风响应对大跨索屋盖结构的风敏感性影响一直是当前风工程研究的热议难题。针对大跨索穹顶屋盖结构,设计制作了缩尺比为1∶250的试验模型,在B类地貌下开展了36组风洞测压试验,研究了全风向角下大跨索穹顶屋盖结构的风压峰值分布规律和典型不利风向角,最后基于风洞试验数据,探究了索穹顶屋盖在不同风速等级下的风振敏感性。结果表明:索穹顶屋盖主要以承载负风压为主;屋面以承载Z向负风振位移响应为主,呈现中心区域向周边下降的变化规律;屋面Z向风振位移响应随风速增大而递增,平均风响应随风速增大呈线性递增;部分风速等级下索穹顶屋盖的脉动风位移响应和总极值位移响应敏感,且风振系数较大;结构屋面响应最大点处风压系数时程傅里叶变换幅值在结构前10阶部分频段为峰值,表明索穹顶屋盖结构存在敏感风速范围,其脉动风响应显著,且与结构模态自振特性密切相关,抗风设计时应找出敏感风速范围,并对响应显著区域加强抗风设计。

The frequency of large-span cable dome structure is dense,and its wind vibration force response is complex.It is always popular in wind engineering to investigate the influence of the fluctuating wind response on the wind sensitivity of the large-span cable dome structure under different wind speeds.For the large-span cable dome roof structure,the test model with the scale ratio of 1∶250 was designed and 36 groups of wind tunnel pressure tests were carried out under Class B landform.The wind pressure peak distribution law and the typical adverse wind direction angles of the large-span cable dome roof structure under all wind direction angles were studied.Finally,based on the wind tunnel test data,the wind-induced vibration sensitivity of the cable dome roof under different wind speed levels was analysed.The results show that the cable dome roof mainly bears negative wind pressure.The roof mainly bears the Z-direction negative wind-induced displacement response,showing the law of decrease from the central area to the periphery.The Z-direction wind-induced displacement response of roof raised with the increase of wind speed,and the average wind response goes up linearly with the increase of wind speed.Under some levels of the wind speed,the fluctuating wind displacement response and the total extreme displacement response of cable dome are sensitive,and the wind vibration coefficient is large.The time history Fourier transform amplitude of the wind pressure coefficient at the maximum point of the structural roof response reaches the peak in the first 10 frequency bands of the structure,indicating that the cable dome roof structure has a sensitive range of the wind speed,and its fluctuating wind response is strong and closely relates to the structural modal natural vibration characteristics.It is necessary to find out the sensitive range of the wind speed and to focus more on the area with significant response while designing the wind resistance.