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

高强度风事件的频率显著增加，例如下击暴流和龙卷风等风暴。然而，目前在加拿大实施的《建筑规范》并没有针对这些类型的极端风事件的具体设计指南。因此，需要更新设计指南，以整合与这些类型的风有关的风速分布、湍流强度和压力波动，并规定位于风暴易发地区的建筑物受到下击暴流和龙卷风影响的临界荷载。目前的研究方案针对这些问题，集中在三个具体方面：下击暴流多向风廓线的模拟，对低层建筑和斜拉桥两种结构(低层建筑和斜拉桥)的下击暴流引起的风荷载的调查，以及最后提出设计规范条款，其中将结合考虑强风对所调查结构的影响的安全系数的校准。下击暴风的分析模拟将作为具有多维风廓线的三维冲击喷流来执行，其倾角以通量相关的雷诺数为特征。下击暴风的湍流性质将被确定为正交谱和同谱，风速波动将根据现有的实验测量进行校准。一旦建立了下击暴流湍流特性，将为大跨度桥梁的颤振和抖振分析提供依据。提出了考虑下击暴流影响的结构气动颤振和抖振力的新公式，以供桥梁设计规范使用。这项研究的长期目标是建议将下击暴流高强度风区的风谱公式纳入新的风设计指南。为下暴风确定的压力也将应用于有开口的低层建筑物，以确定建筑物围护结构破裂的影响，并为建筑物的角落和末端区域规定调整系数。申请者的专长是风能工程领域，她是负责发布日本国家风能设计指南的委员会的积极成员。

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.