Collaborative Research: Experimental Quantification of Tsunami-driven Debris Damming on Structures

该项目将调查建筑物前的碎片堆积，即，在海啸事件期间，碎片筑坝导致海啸流施加在结构上的力增加。为了更好地了解由于筑坝引起的海啸力增加的幅度，导致力增加的机制以及筑坝荷载的变化，将在俄勒冈州州立大学国家科学基金会（NSF）支持的自然灾害工程研究基础设施（NHERI）设施的大浪水槽中对高架建筑物进行实验。更好地了解海啸驱动的碎片筑坝荷载可用于（1）改进现有的设计指南，以建造更安全的建筑物，（2）确定影响碎片筑坝的因素，以确定有助于减少或减轻筑坝荷载的措施，以及（3）改进现有建筑物的海啸脆弱性评估，以表征风险和恢复力。该项目还将包括让高中生参与实验的外联活动，为本科生和研究生提供参与实验和计算建模的研究机会，以及为研究人员和实践工程师举办网络研讨会，以促进研究成果的采用。 这项研究将有助于NSF在国家地震减灾计划（NEHRP）中的作用。大型波浪水槽中的实验将侧重于确定引起海啸驱动的碎片筑坝的机制以及高架结构（如垂直疏散结构）第一层柱子上的相关载荷。 这些机制包括但不限于：碎片-结构、碎片-流动、碎片-碎片相互作用、流动和速度场的变化以及有效建筑物投影面积的变化。这些实验将使用形状、大小、密度和数量各不相同的均质碎片和非均质碎片混合物。一种新的迭代实验设计策略将被用来解决指数大量的潜在的实验条件，并量化的偶然的不确定性的负载。此外，新的无量纲参数将用于量化筑坝的可能性和超过设计筑坝荷载的概率。实验数据分析和补充计算流体动力学模拟的结果将提供关于碎片如何与其他碎片和结构相互作用以及海啸流场（速度和深度）如何因碎片筑坝而变化的新知识。由此产生的数据集将通过NHERI数据仓库（https：//www.example.com）与研究界共享。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。www.DesignSafe-ci.org

This project will investigate how the accumulation of debris in front of buildings, i.e., debris damming, during tsunami events leads to an increase in the forces imposed by tsunami flow on structures. To better understand the magnitude of increase in tsunami forces due to damming, the mechanisms that cause increased forces, and the variability in damming loads, experiments will be conducted on elevated buildings in the large wave flume at the National Science Foundation (NSF)-supported Natural Hazards Engineering Research Infrastructure (NHERI) facility at Oregon State University. A better understanding of tsunami-driven debris damming loads can be used to (1) improve existing design guidelines to construct safer buildings, (2) identify factors that affect debris damming to determine measures that help reduce or mitigate the damming loads, and (3) improve tsunami vulnerability assessment of existing buildings for characterizing risk and resilience. The project will also include outreach activities to engage high school students in the experiments, research opportunities for undergraduate and graduate students to participate in the experiments and computational modeling, and webinars for researchers and practicing engineers to promote the adoption of the research findings. This research will contribute to the NSF role in the National Earthquake Hazards Reduction Program (NEHRP). The experiments in the large wave flume will focus on identifying the mechanisms that cause tsunami-driven debris damming and associated loads on the first floor columns of an elevated structure, such as a vertical evacuation structure. These mechanisms include, but are not limited to, debris-structure, debris-flow, debris-debris interactions, changes in flow and velocity fields, and changes in effective building projected area. The experiments will use homogeneous debris as well as non-homogeneous debris mixtures with varying shapes, sizes, densities, and quantities. A novel iterative experimental design strategy will be used to address the exponentially large number of potential experimental conditions and to quantify the aleatory uncertainty in the loads. Additionally, new dimensionless parameters will be used to quantify the likelihood of damming and the probability of exceeding design damming loads. The results from the analysis of experimental data and supplementary computational fluid dynamics simulations will provide new knowledge on how debris interacts with other debris and the structure, and how tsunami flow fields (speed and depth) change because of debris damming. The resulting data set will be shared with the research community via the NHERI Data Depot (https://www.DesignSafe-ci.org).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.