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

本项目将调查在海啸事件期间，建筑物前面的碎片堆积（即碎片筑坝）如何导致海啸流对建筑物施加的力增加。为了更好地了解由于筑坝引起的海啸力增加的幅度、引起力增加的机制以及筑坝载荷的变化，将在美国国家科学基金会（NSF）支持的俄勒冈州立大学自然灾害工程研究基础设施（NHERI）设施的大波水槽中的高架建筑上进行实验。更好地了解海啸驱动的碎片坝载荷可以用于(1)改进现有的设计指南，以建造更安全的建筑物；(2)确定影响碎片坝的因素，以确定有助于减少或减轻大坝载荷的措施；(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。该项目还将包括吸引高中生参与实验的外展活动，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的网络研讨会，以促进研究成果的采用。这项研究将有助于美国国家科学基金会在国家减少地震灾害计划（NEHRP）中的作用。在大波浪水槽中进行的实验将集中于确定导致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）一楼柱上的相关载荷。这些机制包括但不限于：碎屑-结构、碎屑-流动、碎屑-碎屑相互作用、流场和速度场的变化以及有效建筑投影面积的变化。实验将使用均匀碎片和不同形状、大小、密度和数量的非均匀碎片混合物。一种新的迭代实验设计策略将用于解决指数级的潜在实验条件，并量化载荷的不确定性。此外，新的无量纲参数将用于量化大坝的可能性和超过设计大坝荷载的可能性。实验数据分析和补充计算流体动力学模拟的结果将提供新的知识，说明碎片如何与其他碎片和结构相互作用，以及由于碎片筑坝海啸流场（速度和深度）如何变化。结果数据集将通过NHERI数据仓库（https://www.DesignSafe-ci.org）.This)与研究界共享，该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.