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

高强度风力事件，例如暴雨和龙卷风等风暴的频率显著增加。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制定具体的设计指南。因此，需要对设计指南进行更新，以整合与这些类型的风相关的风速剖面、湍流强度和压力波动，并规定由落爆和龙卷风对位于风暴易发地区的结构所引起的临界载荷。目前的研究计划解决了这些问题，重点关注三个特定方面：下突多向风廓线的模拟，下突对两种类型结构（低层建筑和斜拉桥）的风荷载的研究，最后提出了设计规范条款，将整合有关强风对所研究结构影响的安全系数的校准。下爆风的分析模拟将作为三维冲击射流进行，具有多维风廓线，具有不同的倾斜度，其特征是与通量相关的雷诺数。将确定下暴风的湍流特性，如正交和共谱，风速波动将根据现有的实验测量进行校准。下突湍流特性一旦建立，将为大跨度桥梁颤振分析提供依据。将提出一种新的包括下爆效应在内的结构气动颤振力和抖振力公式，以供桥梁设计规范使用。这项研究的长期目标是为下击高强度风区推荐一种风谱公式，以纳入新的风力设计指南。为下爆风确定的压力也将适用于有开口的低层建筑，以确定建筑围护结构中裂缝的影响，并规定建筑物角落和末端区域的调整因素。申请人的专长是在风力工程领域，她是负责发布日本国家风力设计指南委员会的活跃成员。

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.