On modelling of Typhoon-induced non-stationary wind speed for tall buildings

Typhoon-induced wind around tall buildings may not be stationary because it is a large body of rotating air. A new approach is thus proposed in this paper for characterizing typhoon-induced wind speed. Typhoon-induced non-stationary wind speed is modelled as a deterministic time-varying mean wind speed component plus a zero mean stationary fluctuating wind speed component. The time-varying mean wind speed is naturally extracted from the measured wind speed time history using empirical mode decomposition (EMD). Wind characteristics described in the traditional approach based on a stationary wind model are redefined and extended in the non-stationary wind model. The new approach is then applied to wind data measured at the Di Wang building during Typhoon York. The results show that most of recorded wind samples are non-stationary but they can be decomposed into a time-varying mean wind speed component plus a well-behaved zero mean fluctuating wind speed component admitted as a stationary random process with Gaussian distribution. Other wind characteristics such as probability distribution of fluctuating wind speed, turbulence intensity, gust factor, and wind spectrum obtained by the new approach seem to be more realistic than those gained by the traditional approach.