Field observations on modal properties of two tall buildings under strong wind

This paper presents observations on the identified modal properties of two tall buildings using ambient vibration data collected during strong wind events. A recently developed fast Bayesian frequency domain method is used for modal identification based on the measured ambient data. The approach views modal identification as an inference problem where probability is used as a measure for the relative plausibility of outcomes given a model of the structure and measured data. Focusing on the first three modes, the modal properties of the buildings are identified on non-overlapping time windows during the strong wind events, spanning periods of normal to high wind speeds. Investigation of the identified natural frequencies and damping ratios versus the modal root-mean-square value indicates a significant trend that is statistically repeatable across events.