NTU-CEE Distinguished Seminar Series: Yukio Tamura

Organized By

CEE Seminar Committee

Host By

Professor Chu Jian

Topic

Damping and Natural Frequency in Buildings for Wind-Resistant Design

About the Seminar

Dynamic properties such as natural frequency and damping ratio are essential for simulating wind-induced responses in buildings, with the damping ratio playing a particularly important role in evaluating structural stability. This study first discusses the physical causes of damping, appropriate evaluation techniques, and key considerations for accurate assessment. It then introduces the Japanese Damping Database (JDDB), which contains data from 285 buildings, and presents empirical formulas for natural frequencies and damping ratios.

The variation of damping ratio with amplitude is examined, focusing on the elastic range relevant to wind-resistant design. A theoretical expression for stick-slip damping is also introduced. Although damping is generally believed to increase with amplitude, no evidence supports this within the elastic limit unless damage occurs. Beyond a certain “critical tip drift ratio”, the damping ratio clearly decreases as all contact surfaces become fully mobilized.

While conventional formulas for natural frequency and damping ratio typically rely on limited parameters such as building height and amplitude, this study applies explainable machine learning (XML) to analyze the effects of eight parameters using the JDDB. The results show that building height is the most influential factor for natural frequency, while other factors have lesser impacts. The damping ratio also tends to decrease with increasing height and is significantly influenced by tip displacement, building usage, longitudinal and transverse dimensions, material type, embedment length, and pile length.

About the Speaker

Dr. Yukio TAMURA is a Professor and Advisory Director of the Research Center for Wind Engineering, Environment, and Energy at Chongqing University, China. He also serves as the Honorary Director of the Wind Engineering Research Center at Tokyo Polytechnic University, Japan. From 2007 to 2015, he served as President of the International Association for Wind Engineering (IAWE) and currently holds the position of Honorary Chair of the International Thematic Group on Wind-Related Disaster Risk Reduction under the auspices of the United Nations Office for Disaster Risk Reduction (UNDRR).

Professor Tamura has received numerous prestigious awards, including the ASCE Jack E. Cermak Medal (2004), the ASCE Robert H. Scanlan Medal (2016), and the IAWE Alan Davenport Medal (2016). In recognition of his significant contributions to the field, he has also been honored with other notable distinctions, such as the 2015 Japan Association for Wind Engineering Design Award for his role in the wind-resistant design of the 634m-high Tokyo Sky Tree, the Chinese Government Friendship Award (2017), and the Chinese National Science and Technology Progress Award (2024).

He is a member of several distinguished academies, including 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.

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