Structural Response in Transient Winds of Hurricanes and Downbursts

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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.