RAPID/Collaborative Research: Study of Soil-Structure Interaction Effects on Behavior and Damage to Structures in Washington, DC, during the August 23, 2011 Earthquake

2011年8月23日的弗吉尼亚地震发生在一个区域公认的地震活动区，即“弗吉尼亚中部地震带”。至少从18世纪开始，这个地区就发生了中小型破坏性地震。8月份的地震震级为5.7级，震中位于华盛顿特区西南约135公里的路易莎县。华盛顿特区的许多建筑都受到了严重的破坏，包括史密森学会的博物馆支持中心（MSC）和华盛顿国家纪念碑。两座建筑物的损坏都是出乎意料的。也就是说，与震中附近的其他地区相比，华盛顿特区的震动强度和破坏程度明显上升。本研究是通过对两个重要设施的损坏进行详细分析来调查有助于解释这一趋势的原因。MSC是一个大型仓库综合体，是史密森尼博物馆的主要存储设施，是美国东部许多建筑系统的典型代表。华盛顿纪念碑是世界上最高的石头建筑和世界上最高的方尖碑，同时也具有国家历史意义。初步分析表明，这两个结构的破坏与关键工程因素的相互作用有关，包括它们的动力结构特征和华盛顿特区地区特定的地质和岩土（土壤）条件。这项研究是里海大学、弗吉尼亚理工大学和美国地质调查局（USGS）的研究人员共同努力的结果。研究活动包括结构和岩土工程任务。结构工程活动包括从MSC和华盛顿纪念碑收集易腐损伤数据，进行现场振动试验以建立这两种结构的动力特性，并开发先进的数值模型。主要的岩土工程任务包括与美国地质勘探局合作，进行现场测试，以表征这些地点的动态行为，并对5.7级地震期间发生的地震震动进行详细的数值模拟。总的来说，研究人员将使用结构模型、动态场地参数和地面震动模拟对这两个设施进行详细分析，以解释在5.7级地震中观察到的损害。研究结果将通过使用模型来模拟不同的地震情景，以更好地了解和传达发生在华盛顿特区或该地区其他人口稠密地区附近的5.7级或更大级别地震的潜在影响。结果将与工程师、利益相关者和工程社区内外的决策者共享。正在研究的这两个结构为分析美国东海岸非抗震结构的行为提供了一个独特的机会。我们的深入研究将为建立美国东部建筑在地震灾害中的脆弱性以及确保其恢复能力的改造需求提供专业见解。特别重要的是，这项工作将促进美国东部建筑规范和设计程序的进步。

The Virginia earthquake of August 23, 2011 occurred within a regionally well-established zone of earthquake activity, the "Central Virginia Seismic Zone". This area has produced small and moderate damaging earthquakes since at least as far back as the 18th century. The magnitude of the August earthquake was 5.7, and the epicenter was located in Louisa County, about 135 km southwest of Washington DC. Significant damage occurred to a number of structures in Washington, DC, including the Smithsonian Institute's Museum Support Center (MSC) and the Washington National Monument. Damage to both structures was unexpected. That is, there was a marked uptick in the shaking intensity and damages in the Washington, DC, region relative to other areas located much closer to the epicenter. This research is to investigate reasons that help explain this trend by performing detailed analyses of two important facilities that were damaged. The MSC, a large warehouse complex that serves as the main storage facility for the Smithsonian, is typical of many building systems in the eastern US. The Washington Monument is the world's tallest stone structure and the world's tallest obelisk, while also being of national historical significance. Preliminary analyses indicate that the damage to both of these structures is related to the interaction of key engineering factors, including their dynamic structural characteristics and the specific geologic and geotechnical (soil) conditions underlying the Washington, DC, area.The study is a collaborative effort between researchers at Lehigh University, Virginia Tech, and the US Geological Survey (USGS). Research activities involve both structural and geotechnical tasks. The structural engineering activities include gathering perishable damage data from the MSC and Washington Monuments, performing field vibration tests to establish the dynamic characteristics of these two structures, and developing advanced numerical models. The main geotechnical tasks involve working with USGS to perform field tests to characterize the dynamic behavior of the sites, and developing a detailed numerical simulation of the earthquake shaking that occurred during the magnitude 5.7 earthquake. Collectively, the researchers will use the structural models, dynamic site parameters, and ground shaking simulations to perform detailed analyses of both facilities to explain the observed damages during the magnitude 5.7 earthquake. The findings will then be extended by using the models to simulate different earthquake scenarios to better understand and communicate the potential impacts of the magnitude 5.7 or an even larger magnitude earthquake occurring closer to Washington, DC, or other populated areas in the region. Results will be shared with engineers, stakeholders, and decision makers in the engineering community and beyond. The two structures being studied represent a unique opportunity to analyze the behavior of east-coast US structures not designed to resist earthquakes. Our in-depth study will be insightful to the profession for establishing the vulnerability of eastern US structures to earthquake hazards and needs for renovation to ensure their resiliency. Of particular importance, this work will promote advancements in building codes and design procedures specific to the eastern US.