Benchmark Study of Tornado Wind Loading on Low-Rise Buildings with Consideration of Internal Pressure

从历史上看，龙卷风是美国最具破坏性的自然灾害之一，最近几次主要龙卷风造成的破坏和死亡人数可以看出，包括2011年密苏里州乔普林和阿拉巴马州塔斯卡卢萨-伯明翰龙卷风，2013年俄克拉荷马州摩尔龙卷风和2015年德克萨斯州达拉斯地区龙卷风。正如龙卷风灾害调查一再显示的那样，龙卷风造成的损失和死亡往往是由于对低层建筑的破坏。造成这种建筑破坏的一个关键因素是，许多低层建筑的设计只针对地球表面附近沿直线传播的风，而不是针对可能更具破坏性的旋转龙卷风，这主要是由于对龙卷风和龙卷风对结构的载荷了解不足。本研究的目的是建立综合表征旋转龙卷风风荷载及其对低层建筑影响的计算模型。工程师可以使用这些模型对低层建筑进行基于性能的评估，以减少龙卷风造成的破坏和死亡。为了提高人们对自然灾害（包括龙卷风）对建筑物和社区的影响的认识，这项研究将被整合到德克萨斯理工大学（TTU）现有项目的教育和推广活动中，例如TTU国家风能研究所风科学与工程博士项目提供的课程，以及正在进行的推广活动，包括4-H指导计划、科学营和拉伯克的年度严重意识日。为了实现这一研究目标，该项目将在TTU的大型龙卷风模拟器模拟的各种类型的龙卷风漩涡中测试两种屋顶类型的低层建筑模型，并在佛罗里达大学的nsf支持的自然灾害工程研究基础设施（NHERI）边界层风洞中模拟直线风，以提供两个基准数据集。这两个数据集将用于量化龙卷风和边界层型直线风的载荷之间的差异。重点将放在建筑物内部压力的影响，以及龙卷风载荷的非平稳和非高斯性质，这些特性是由空间变化的风速和龙卷风漩涡中的静压赤字的转换所引入的。在此基础上，采用基于离散小波变换和高斯滤波的创新方法对低层建筑的非平稳、动态龙卷风风荷载进行表征、建模和模拟，从而对荷载效应进行概率评估。项目数据将在NHERI数据仓库中提供，网址为https://www.designsafe-ci.org/。

Tornadoes are historically among the most devastating natural hazards in the United States, as observed by the damage and fatalities during recent major tornadoes, including the Joplin, Missouri and Tuscaloosa-Birmingham, Alabama tornadoes in 2011, the Moore, Oklahoma tornado in 2013, and the Dallas, Texas area tornado in 2015. As post-tornado disaster surveys have repeatedly revealed, tornado-induced losses and fatalities are often due to damage to low-rise buildings. A critical factor contributing to such building damage is that many low-rise buildings are designed only for winds that travel mostly along a straight line near the earth's surface, and not for the rotating tornado winds that are potentially more damaging, primarily due to inadequate understanding of tornadoes and tornado wind loading on structures. The goal of this research is to formulate computational models that comprehensively characterize rotating tornado wind loading and the impact of such wind loading on low-rise buildings. Such models can be used by engineers to conduct performance-based evaluation of low-rise buildings subjected to tornado hazard as a way to reduce damage and fatalities. To raise awareness of the impact of natural hazards, including tornadoes, on buildings and communities, this research will be integrated into education and outreach activities within existing programs at Texas Tech University (TTU), such as courses offered by TTU's National Wind Institute Wind Science and Engineering Ph.D. program and ongoing outreach activities, including a 4-H Mentoring Program, Science Camp, and Lubbock's Annual Severe Awareness Day. To achieve this research goal, this project will test models of low-rise buildings with two roof types in various types of tornadic vortices simulated in a large-scale tornado simulator at TTU and straight-line winds simulated in the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) boundary layer wind tunnel at the University of Florida to provide two benchmark datasets. These two datasets will be used to quantify the differences between the loadings by tornado and boundary-layer-type straight-line winds. The focus will be placed on the effects of building internal pressure and the nonstationary and non-Gaussian nature of tornado loading introduced by the translation of spatially varying wind speed and static pressure deficit in tornado vortices. On this basis, an innovative approach based on discrete wavelet transform and Gaussian filtering will be used to characterize, model, and simulate nonstationary, dynamic tornado wind loading on low-rise buildings to enable probabilistic evaluation of the loading effects. Project data will be made available in the NHERI Data Depot at https://www.designsafe-ci.org/.