Damping ratios and natural frequencies of buildings for wind resistance design

Yukio Tamura. PhD

Professor 

Advisory Director of Research Center of Wind Engineering, Environmental and Energy

Chongqing University, China

Friday, May 16 | 11 a.m. | 140 Ketter Hall

Physical causes of damping in buildings, the importance of appropriate use of damping evaluation techniques, and points to note for accurate evaluation of damping are first discussed. Next, the Japanese Damping Database collected from 285 buildings is introduced and empirical formulae of natural frequencies and damping ratios are derived. Then, the variation of damping ratio with amplitude is discussed, especially in the amplitude range relevant to wind-resistant design of buildings, i.e. within the elastic limit. A theoretical expression for damping due to stick-slip components is derived and introduced. 

The general belief is that damping increases with amplitude, but it is emphasized that there is no evidence of increasing damping ratio in the very high amplitude range within the elastic limit of main frames, unless there is damage to secondary members or architectural finishings. The damping ratio decreases with amplitude from a certain tip drift ratio defined as “critical tip drift ratio” after all friction surfaces between primary/structural and secondary/non-structural members have been mobilized. Finally, the contributions of various building parameters, not only the building height or tip displacement, to dynamic properties are discussed using the Explainable Machine Learning technique (XML) based on the Japanese Damping Database.

Yukio Tamura is a Professor and the Advisory Director of Research Center of Wind Engineering, Environment and Energy, Chongqing University, China. He is also the Honorary Director of the Wind Engineering Research Center of Tokyo Polytechnic University, Japan. He served as the President of the International Association for Wind Engineering for eight years from 2007 to 2015. He is now serving as the Honorary Chair of the International Thematic Group for Wind-Related Disaster Risk Reduction under the auspices of the United Nations Office of Disaster Risk Reduction. He received the ASCE Jack E. Cermak Medal in 2004, the ASCE Robert H. Scanlan Medal in 2016, and the IAWE Alan Davenport Medal in 2016.

In addition, due to his various professional contributions, he has received other important awards, including the Japan Association for Wind Engineering 2015 Design Award for his contribution to the wind resistant design of the Tokyo Sky Tree, the Chinese Government Friendship Award in 2017, Chinese National Science and Technology Development Award in 2024. He is a member of the Engineering Academy of Japan, a Foreign Fellow of the Indian National Academy of Engineering, and an International Member of the Chinese Academy of Engineering.