Structural Response in Transient Winds of Hurricanes and Downbursts

在飓风和暴雨期间，为了确保公共安全以及桥梁和基础设施的完整性，需要对风致效应进行准确建模。极端风的瞬变特征既不能很好地理解，也不能很好地刻画，这就给事前分析带来了困难。本项目致力于基础研究，以开发分析模型来分析结构在飓风和下击暴风中的反应。研究结果将有助于制定用于评估柔性结构响应的设计标准。将开发和部署风场模拟器作为在线工具，使设计人员、研究人员和教育工作者能够模拟飓风和下击暴风的影响，研究的主要目标是开发有效的分析工具来表征和模拟飓风和下击暴流非天气事件期间的非平稳风速场和瞬时风荷载效应。将开发一个系统的时频分析和综合框架，将时不变(传统的)和/或时变的空间相干性整合到模拟的非平稳风速场中。该框架将有助于理解风-结构相互作用分析的暂态风荷载效应的基本物理原理。这项研究将评估非定常风输入对结构响应的静态、准静态和动态影响，并研究气动参数的修改。基于具有各种空间相关性的非平稳风场的联合接受函数及其对结构响应的影响将被研究。希尔伯特和小波技术将被用于非平稳风速场的分析和合成，并将对其有效性进行评估。飓风和下击暴流的非平稳特征将使用现场测量、实验和数值模拟的数据进行研究。瞬变空气动力学将使用柔性桥梁来说明，结果也与建筑物和其他结构的评估相关。

The assurance of public safety and the integrity of bridges and infrastructure during hurricanes and downbursts require accurate modeling of wind-induced effects. The transient characteristics of extreme winds are neither well understood nor characterized, which makes pre-event analysis difficult. This project pursues fundamental research to develop analytical model to analyze structural response in hurricane and downburst winds. Results will contribute to design standards that are used to assess response of flexible structures. A wind-field simulator will be developed and deployed as an on-line tool to enable designers, researchers and educators to simulate the effects of hurricane and downburst winds.The primary goal of the research is to develop effective analysis tool to characterize and simulate the nonstationary wind-velocity fields and transient wind-load effects during non-synoptic events of hurricanes and downbursts. A systematic time-frequency analysis and synthesis framework, which can integrate the time-invariant (traditional) and/or time-variant spatial coherence into the simulated nonstationary wind-velocity fields, will be developed. The framework will facilitate an understanding of the underlying physics of transient wind-load effects for wind-structure interaction analysis. The study will assess the impact of nonstationary wind inputs in terms of their static, quasi-static and dynamic effects on structural response, and investigate modification of aerodynamic parameters. Joint acceptance functions, based on the nonstationary wind fields with various spatial coherences, and their effects on structural response will be examined. The Hilbert and wavelet techniques will be employed for the analysis and synthesis of nonstationary wind-velocity fields, and their efficacy will be assessed. The nonstationary features of hurricanes and downbursts will be investigated using data from field measurements, experiments, and numerical simulations. The transient aerodynamics will be illustrated using flexible bridges, with results also being relevant to the assessment of buildings and other structures.