基于风压谱拟合的电厂大跨度屋盖风振特性频域分析

Frequency Domain Analysis of Wind-Induced Vibration Characteristics of Long-Span Roof of Power Plant Based on Wind Pressure Spectrum Fitting

大跨度屋盖结构属于风敏感结构,风与结构的相互作用十分复杂,风荷载常常是设计的主要控制荷载之一。以某电厂大跨度屋盖为研究背景,获得了结构的自振动力特性。基于风压谱拟合和风压时程本征正交分解(proper orthogonal decomposition,POD)重构原理,提出了一种修正的频域法,该法直接采用风洞试验得到的风压数据建立屋盖整体风压模型,通过快速傅里叶变换(fast fourier transform,FFT)转化为风压谱,在精确拟合屋盖计算点风压功率谱的基础上,获得屋盖结构的风致响应,同时推导了屋盖无量纲风压谱的表达公式。研究了结构位移均方根值和加速度均方根值的分布特点,同时得出了屋盖的风振系数分布特点。研究结果表明修正频域法抛弃了准定常假设,计算结果具有较高精度,可以作为大跨度屋盖结构抗风设计的参考。

With the complex interaction between wind and structure, the long-span roof structure belongs to wind-sensitive structures and the wind load becomes the main problem of the structure design. Taking a long-span roof of power plant as research background, the vibration characteristics of the structure were obtained. Based on the wind pressure spectrum fitting and the proper orthogonal decomposition （POD） reconstruction principle of wind pressure time-history, a modified frequency domain analysis method was presented. This method used the wind pressure data obtained in wind tunnel tests to establish the overall wind pressure model for roof, and turned it into wind pressure spectrum through fast Fourier transform （~）. Then the wind-induced dynamic response of roof structure was obtained based on the accurate fitting of wind pressure power spectrum, and the dimensionless formula of wind pressure spectrum was derived. Finally, the distribution characteristics of the root mean square （RMS） values of structural displacement and acceleration were studied to get the distribution characteristics of the wind-induced vibration coefficient of the roof. The results show that modified frequency domain method, which abandons the quasi-steady assumption, has higher reliability, and can be used as references for the wind-resistant design of long-span roof structures.