Collaborative Research: Characterization, Modeling and Uncertainty Analysis of Tornado Wind and Its Effects on Buildings

合作研究：龙卷风及其对建筑物影响的表征、建模和不确定性分析

• 批准号: 1400251
• 负责人: Partha Sarkar
• 金额: $ 25万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1400251&HistoricalAwards=false
• 关键词: Collaborative; Research; Characterization; Modeling; Uncertainty

The devastation from recent tornadoes in Joplin, Missouri, and Tuscaloosa, Alabama, in 2011 and in Moore, Oklahoma, in 2013 highlight the national vulnerability to these windstorm events. Direct measurement of tornado wind speed near the ground level is difficult to obtain due to its unpredictable nature and destructive force. Current practice is to estimate wind speed based on observed damage to structures and non-structures using the Enhanced Fujita (EF) Scale, which is widely accepted in climatological study, risk analysis, and design of critical facilities. However, such damage-based methods have a great degree of uncertainty. Critical knowledge gaps exist about spatial and temporal distributions of wind flow near the ground level and how wind flow interacts with the terrain and structures. To address these knowledge gaps, this research will characterize, model, and analyze uncertainties in tornado wind and its effects on buildings. This research will lead to better understanding of the effects of tornado and terrain parameters on near-ground wind field structures, the transient aerodynamic force of tornado wind on building designs, and the uncertainties in building performance subject to tornado wind. This knowledge will contribute toward the foundation for developing performance-based building code provisions to mitigate the impact of tornado wind loads on buildings.This research aims to make the following three knowledge advances. First, knowledge for understanding the tornado wind field will be advanced through a systematic study of the effects of tornado and terrain parameters. This study will fill an important gap between a tornado's structure aloft and ground level damages and will provide the physics-based evidence critically needed for updating the EF Scale. Fragility functions will be developed to recalibrate the expected, upper bound, and lower bound wind speeds for Degree of Damage in the EF Scale. Second, understanding of pressure and load effects of non-synoptic winds, including tornadoes and thunderstorms, will be advanced with the development of transient aerodynamic force models. These models will not only enable better characterization of load effects under a non-stationary vortex but also will build a bridge to results accumulated from decades of research in stationary boundary layer wind. Third, a new framework for characterizing and quantifying uncertainties of the tornado wind load chain on buildings will be developed and validated with finite element models and post-storm damage surveys. This framework will permit the integration of uncertainties, including those of building properties and construction quality, in assessing building vulnerability, laying the foundation for performance-based building code provisions for tornadoes. This research is enabled by a confluence of latest advances in tornado simulation, data acquisition and modeling capabilities, full-scale studies of the tornado vortex, near-ground measurements of tornado wind, and theories in non-stationarity, many of which were not available a few years ago.

2011年，最近在乔普林（Joplin）和阿拉巴马州托斯卡卢萨（Tuscaloosa）的龙卷风和俄克拉荷马州摩尔（Moore）的龙卷风的破坏重点介绍了民族对这些风暴事件的脆弱性。 由于其不可预测的性质和破坏力，很难获得接近地面的龙卷风速度的直接测量。当前的实践是根据观察到的富士（EF）量表对结构和非结构的损害进行估算的速度，该量表在气候研究，风险分析和关键设施的设计中被广泛接受。 但是，这种基于损害的方法具有很大程度的不确定性。关于地面水平附近风流的空间和时间分布以及风流与地形和结构的相互作用的关键知识差距。为了解决这些知识差距，这项研究将表征，建模和分析龙卷风风及其对建筑物的影响。这项研究将使人们更好地了解龙卷风和地形参数对近场风场结构的影响，龙卷风风的瞬态空气动力学对建筑物设计的瞬态空气动力以及建筑性能的不确定性，但遭到龙卷风风。 这些知识将有助于开发基于绩效的建筑法规规定，以减轻龙卷风风负载对建筑物的影响。这项研究旨在提高以下三个知识进步。首先，通过对龙卷风和地形参数的影响进行系统的研究，将提出了解龙卷风风场的知识。这项研究将填补龙卷风的结构上的重要差距和地面损失，并将为更新EF量表提供至关重要的证据。将开发脆弱功能，以重新校准预期的，上限和下限风速，以在EF量表中损害程度。其次，随着瞬态空气动力模型的发展，将提出对包括龙卷风和雷暴在内的非同步风的压力和负载效应的理解。 这些模型不仅可以在非平稳涡流下更好地表征负载效应，而且还将建立一个桥梁，以桥梁在固定边界层风中的数十年研究中积累的结果。第三，将开发和量化建筑物上龙卷风风负荷链的不确定性的新框架，并使用有限的元素模型和验证后的伤害调查来开发和验证。该框架将允许整合不确定性，包括建筑物和建筑质量的框架，以评估建筑脆弱性，为龙卷风基于绩效的建筑法规规定奠定基础。龙卷风模拟，数据采集和建模能力的最新进展，对龙卷风涡流的全面研究，对龙卷风风的近地测量以及非平稳性的理论，其中许多是在几年以前，这项研究的最新进展是通过龙卷风模拟，数据采集和建模能力的最新进展的融合来实现这项研究的。