The effect of multidirectional high intensity winds on aerodynamic response of structures

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The frequency of high intensity wind events, e.g., windstorms such as downbursts and tornadoes, has increased significantly. However, the Building Codes, currently in place in Canada do not have specific design guidelines for these types of extreme wind events. Therefore, an update of the design guidelines is required to integrate wind speed profiles, turbulence intensities and pressure fluctuations associated with these types of winds and to prescribe critical loads induced by downbursts and tornadoes on the structures located in windstorms prone regions. The current research proposal addresses these issues, focusing on three particular aspects: simulation of downburst multidirectional wind profile, investigation of wind loads induced by downbursts on two types of structures: low-rise buildings and cable-stayed bridges and finally proposing design code provisions that would integrate calibration of safety factors in regard to the effect of high intensity winds on the investigated structures. Analytical simulations of downburst winds will be performed as 3-D impinging jets with multi - dimensional wind profiles, of various inclinations characterized by a flux-dependent Reynolds number. Turbulence properties as quadrature and cospectrum for downburst winds will be determined wind velocity fluctuations will be calibrated against existent experimental measurements. Once established the downburst turbulence properties will serve for the flutter and buffeting analysis of long span bridges. A new formulation of aerodynamic flutter and buffeting forces on structures, which will include the downburst effect will be proposed for the use of Bridges Design Codes. The long-term objective of this research is to recommend a formulation of wind spectrum for downburst high intensity winds regions to be included in the new wind design guidelines. The pressure determined for downburst winds will also be applied to low-rise buildings with openings for determining the effect of breaches in the building envelop and for prescribing adjustment factors for corner and end zones of the buildings. The applicant's expertise is in the field of wind engineering, and she is an active member of the committee responsible for issuing the Japanese National Wind Design Guide.