Abstract：Most super-tall buildings have the natural frequencies of the first two sway modes being very close to each other. For this type of structures, it has been well recognized that the modal correlation effects cannot be ignored in their wind response analysis. However, the current available methods of modal combinations, SRSS and CQC methods, are found to be inadequate to address the modal correlations for wind effects, and the results with these methods can lead to incorrect prediction on wind response or cause confusion in structural optimization design. This paper discusses the insufficient of these two methods both theoretically and numerically. While SRSS method totally neglects the modal correlations, CQC method takes into account of modal correlations for magnitude but overlooks their phase correlations. Therefore CQC method often results in overly conservative estimates on wind responses. Based on fundamental principles of random vibrations, a new method of modal combinations is proposed in this paper. The new method makes use of information from cross-spectrum of aerodynamic forces to precisely estimate the modal correlations in both magnitude and phase angles, and is therefore referred as “CS method”. Owing to its clear presentation in principle and easy adoption in calculation, this method is ready for engineering applications. Time domain simulation validates the precision and reliability of this new method.
汤昱薇1，谢霁明2. 高层建筑风振分析中的模态组合问题[J]. 振动与冲击, 2017, 36(15): 16-21.
TANG Yuwei1XIE Jiming2. Modal Combinations in Prediction of Wind-Induced Building Responses. JOURNAL OF VIBRATION AND SHOCK, 2017, 36(15): 16-21.
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