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Wind and Structures
  Volume 21, Number 2, August 2015 , pages 159-182
DOI: https://doi.org/10.12989/was.2015.21.2.159
 


Amplitude dependency of damping of tall structures by the random decrement technique
An Xu, Zhuangning Xie, Ming Gu and Jiurong Wu

 
Abstract
    This study focuses on the amplitude dependency of damping of tall structures by the random decrement technique (RDT). Many researchers have adopted RDT to establish the amplitude dependency of damping ratios in super-tall buildings under strong wind loads. In this study, a series of simulated examples were analyzed to examine the reliability of this method. Results show that damping ratios increase as vibration amplitudes increase in several cases; however, the damping ratios in the simulated signals were preset as constants. This finding reveals that this method and the derived amplitude-dependent damping ratio characteristics are unreliable. Moreover, this method would obviously yield misleading results if the simulated signals contain Gaussian white noise. Full-scale measurements on a super-tall building were conducted during four typhoons, and the recorded data were analyzed to observe the amplitude dependency of damping ratio. Relatively wide scatter is observed in the resulting damping ratios, and the damping ratios do not appear to have an obvious nonlinear relationship with vibration amplitude. Numerical simulation and field measurement results indicate that the widely-used method for establishing the amplitude-dependent damping characteristics of super-tall buildings and the conclusions derived from it might be questionable at the least. More field-measured data must be collected under strong wind loads, and the damping characteristics of super-tall buildings should be investigated further.
 
Key Words
    tall building; wind effect; damping ratio; full-scale measurement; wind-induced vibration; random decrement technique
 
Address
An Xu: State Key Laboratory of Subtropical Building Science, South China University of Technology,
Guangzhou, 510641, China;
Engineering Technology Research and Development Center for Structural Wind Resistance and Health Monitoring in Guangdong Province, Guangzhou University, Guangzhou, 510006, China
Zhuangning Xie:State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou, 510641, China
Ming Gu: State Key Laboratory of Subtropical Building Science, South China University of Technology,
Guangzhou, 510641, China;
State Key laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai, 200092, China
Jiurong Wu: State Key laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai, 200092, China

 

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