Characterization of translating tornado-induced pressures and responses of a low-rise building frame based on measurement data

Abstract

This study presents an analysis and characterization of dynamic wind pressures and internal forces of a low-rise building frame using measurement data obtained from a tornado simulator. The deterministic time-varying mean pressure component is extracted from the time history record using discrete wavelet transformation (DWT) approach. A continuous wavelet transformation (CWT) based approach is employed for determining the evolutionary power spectral density (EPSD) functions and time-varying standard deviation (STD) as well as co-variance of dynamic pressures. The results showed that the characteristics of dynamic pressures are strongly affected by the location of tornado, and are very different from those under straight-line wind. The pressure drop caused by tornado vortex plays a key role in defining the pressure characteristics. The building frame responses are also calculated from the statistics of pressures. The equivalent static wind loads (ESWLs) causing peak responses are defined by using the gust response factor approach. The effect of translation speed of tornado vortex is also investigated. The translating tornado vortex leads to a delay of occurrence of maximum time-varying mean and STD, and reduction in maximum STD thus peak response. It also makes the energy distribution of pressure fluctuations shifted to higher frequencies with a broader power spectrum. Finally, it is shown that the tornado-induced responses are significantly higher than those from ASCE 7-10.