Transient loads on buildings in microburst and tornado winds

This paper presents both quasi-steady and transient wind load effects on a cubic building in a microburst and a tornado. Large eddy simulation (LES) was used to simulate the loading effects of a translating microburst with a 0.20-m-diameter jet at four different translating velocities on a 25 mm cube. The results of the numerical simulation were compared with data from a laboratory microburst simulator. The numerical simulation predicted an increase in drag forces with increase in microburst translation speed. The transient loading effects on a 229 mm cubic building from a translating tornado were also simulated in a laboratory for two different vortex core diameters and two translating speeds and the peak loads were studied. Results for the cubic building were compared with that of a tall building under the same loading conditions. Finally, peak loads and peak moments measured in this study were compared to the corresponding values specified in ASCE 7-05 [2006. Minimum Design Loads for Buildings and Other Structures, 2006. ASCE Standard, SEI/ASCE 7-05, American Society of Civil Engineers] and found to exceed them by a factor of 1.5 or more for buildings located in tornado alley of the United States subjected to tornadoes of F2 or higher intensity.