Wave Loads and Structural Fragility Behind Impermeable and Permeable Obstacles

风暴和海啸的淹没对美国和世界各地的建筑物和基础设施造成了极大的破坏。减少损害和总体风险缓解仍然是目前和未来沿海社区的优先事项，但这些目标在某种程度上受到工程设计和分析工具的限制。众所周知，在建筑物或植被背后，风暴和海啸造成的破坏会减少，但事实证明，将这些一般知识转化为工程师和规划者的具体指导方针和标准是令人惊讶的困难。该项目将使用理论、数值模型以及现场和实验室测量的结果来调查掩体结构背后的损害减少程度。这一分析的两个显著特点将是考虑在活动期间保护障碍物退化，以及一个概率分析框架，允许针对不同级别的风险进行设计。对有遮挡结构的荷载进行有用的量化，将消除准确设计和规划淹没事件的主要障碍。该项目将有助于改进负荷估算，其方法将直接适用于许多工程设计实例。来自风暴或海啸的地震、淹没事件(IE)负荷可在O(10米)的尺度上变化，并受周围自然和建成环境的极大影响。计算局部危险和局部荷载的不确定性仍然是确定规划和结构设计脆弱性的最大障碍：与裸地条件相比，障碍物后面的荷载显著减少，但这些减少还不能在一般情况下量化。考虑到一些障碍物可能对水流(植被)具有渗透性，或者可能在IE过程中降解，改变负荷，预测变得更加困难。该项目将使用(1)比例和理论分析；(2)计算流体力学模拟；(3)结构分析；(4)现有的现场和实验室数据，检查位于单排障碍物后面的结构的IE危险强度、载荷和脆弱性。分析将通过对障碍物本身的脆弱性建模进一步考虑障碍物退化的影响。结果将使用替代模型考虑不确定性，这将阐明载荷和脆弱性不确定性中的主要因素，并将提出可能改进结果的途径。

Inundation from storm waves and tsunamis has caused great damage to buildings and infrastructure both in the United States and worldwide. Reduction of damage and overall risk mitigation remain priorities for coastal communities now and in the future, but these goals are in some ways limited by engineering design and analysis tools. Damage from storm waves and tsunamis is well known to be diminished behind structures or vegetation, but it has proven surprisingly difficult to translate this general knowledge to specific guidelines and standards for engineers and planners. This project will use theory, numerical models, and results from field and laboratory measurements to investigate the degree of damage reduction behind sheltering structures. Two notable features of this analysis will be the consideration of sheltering obstacle degradation during an event, and a framework for probabilistic analysis that will allow design for different levels of risk. Useful quantification of loading for sheltered structures will remove a major impediment to accurate design and planning for inundation events. This project will help to improve load estimates in ways that will be directly applicable to many instances of engineering design.Unlike hazards such as earthquakes, Inundation Event (IE) loading from storm waves or tsunamis can vary on scales of O(10m), and is greatly affected by the surrounding natural and built environments. Uncertainty in computing the local hazard and local loading remains the greatest obstacle in determining fragility for planning and structural design: Loads behind obstacles have been shown to decrease significantly when compared those from bare-earth conditions, but these decreases cannot yet be quantified for general conditions. Prediction becomes even more difficult when considering that some obstacles may be permeable to flow (vegetation), or may degrade over the course of the IE, changing loading. This project will examine IE hazard intensities, loading, and fragility for structures located behind a single row of obstacles using (1) Scaling and theoretical analyses; (2) Computational fluid dynamics simulations; (3) Structural analyses; (4) Existing field and laboratory data. Analyses will further consider the effects of obstacle degradation using fragility modeling of the obstacle itself. Results will consider uncertainties using surrogate modeling, which will both illuminate the major factors in loading and fragility uncertainties, and will suggest avenues through which results might be improved.