高层建筑顺风向风振动力反应时程分析

Evaluation of Time History of Wind Induced Vibration in the Wind Blowing Direction on High Rise Buildings

采用了谐波叠加法模拟作用在结构上的顺风向脉动风压,同时为了能反映作用在迎风面不同点上脉动风压的相关特性,首先生成脉动风速互谱密度矩阵,然后采用三角分解法进行分解,再以此生成脉动风压作为输入脉动风荷载,采用Newmark方法计算结构的动力反应时程.对两栋高层建筑的风振反应时程计算结果表明,本方法得到的结构动力反应均方根值与建筑结构荷载规范中采用的谱分析结果有较好的吻合性;风振反应以共振反应为主,非共振反应值占次要的部分.这与谱分析法得出的结论也是一致的,说明了利用谐波叠加法模拟脉动风压时程的准确性.这对于正确估算结构的风振反应值,为高层建筑风振控制措施设计提供参考依据是有一定意义的.

In order to derive the time history of dynamic response of high rise buildings under wind pressure fluctuation load, the method of harmonic wave superposition has been used to generate the time history of wind pressure fluctuation in wind blowing direction according to Davenport fluctuating velocity spectrum density function. The Cholesky factorization is adopted to the matrix of cross spectrum function to take the relativity of pressure fluctuation into consideration. In the computation approach, the Newmark step-by-step method is used to derive the time history of dynamic response. Evaluation work has been done for a 68m building and a 180m building and the results show that they correspond well to those obtained with the frequency domain method which has been used in current designing code. It seems that the resonant response makes the significant part of the total dynamic response, the same conclusion as in the case of frequency domain method. The correspondence of the data shows that the harmonic wave superposition method is an effective method to generate time history of man - made pressure fluctuation. The method can be used as a meaningful reference for wind vibration control design and the modification of relative specifications in desigining code.