NEESR-SG: Seismic Performance Assessment in Dense Urban Environments

该奖项是美国国家科学基金会08-519计划征集活动的成果。地震工程模拟研究网络(NEESR)？该竞赛包括加州大学伯克利分校(牵头机构)、纽约州立大学布法罗分校(分奖)、加州大学戴维斯分校(分奖)、加州大学圣地亚哥分校(分奖)、加州理工州立大学圣路易斯·奥比斯波分奖(分奖)和地震工程研究大学联盟(分奖)。该项目将利用加州大学戴维斯分校的NEES设备(加州大学戴维斯分校的土工离心机设施)。在我们的城市，建筑是以集群(城市街区)的形式建造的。理想情况下，它们的设计应该像建筑群一样抵抗地震力，因为一座建筑的反应会影响到邻近建筑的反应。然而，在当前的设计实践中，密集分布的建筑之间的相互作用没有被考虑到，因为建筑通常被设计为隔离结构。土-结构相互作用(SSI)对密集的中低层建筑的影响知之甚少。例如，目前还不清楚不同大小的地下室会如何影响地面对这些建筑的震动。最近的地震破坏了城市中的建筑群，但由于缺乏关于地面运动和建筑物性能的记录，很难从这些观测中吸取教训。然而，一个真实规模的离心机试验的综合计划，其中输入运动，地面条件，地面反应和结构反应可以被仔细跟踪，然后对这些模型试验进行反向分析，可以用来加强专业？S对密集城市环境中建筑物的SSI效应的理解。NEES UC Davis离心机的独特功能将用于促进我们对建筑群SSI影响的了解，以便做出可靠的评估。在离心机中，一个装有土壤和模型建筑的盒子以50g的旋转加速度旋转，使2英尺厚的土壤具有与100英尺厚的土壤相同的应力。建筑模型的比例也是相似的，因此在这些实验中可以测量真实的响应。测试计划将开发一个记录良好的模型数据库？病历？在密集的城市环境中，在有和没有地面崩塌的情况下，经历中度和严重地面震动的地点的建筑性能。然后，研究人员可以利用这些实验结果来提高我们对这些现象的理解和分析它们的能力。物理实验和数值模拟将使我们能够就建筑群在地震中的表现为设计师和政策制定者提供指导。该项目将促进基础科学和工程学知识的发展，为岩土工程和结构工程学科带来巨大的智力利益。这两个学科都将促进和部署基于性能的综合抗震设计和稳健的损失估计方法，并从中受益。该项目还将培训博士生，从教学大学引进本科生，吸引代表性不足的学生，影响建筑规范的制定和基于性能的抗震设计，并通过强调网络媒体接触到广泛的最终用户。我们还将把解决这一现实问题的挑战转化为本科生(和其他人)通过？摇动一个城市街区？振动台比赛，让学生考虑邻近结构和土壤对抗震性能的影响。该项目的数据将通过NEES数据库(http://www.nees.org).)提供

This award is an outcome of the NSF 08-519 program solicitation ?George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)? competition and includes the University of California, Berkeley (lead institution), University of Buffalo-SUNY (subaward), University of California, Davis (subaward), University of California, San Diego (subaward), California Polytechnic State University, San Luis Obispo (subaward), and the Consortium of Universities for Research in Earthquake Engineering (subaward). This project will utilize the NEES equipment site at the University of California, Davis (the UC Davis Geotechnical Centrifuge Facility). In our cities, buildings are constructed in clusters (the city block). Ideally, they should be designed to resist earthquake forces as clusters of buildings, because the response of one building can affect the response of neighboring buildings. However, the interactions between densely spaced buildings are not captured in current design practice, because buildings are typically designed as isolated structures. Soil-structure interaction (SSI) effects on closely spaced low- and medium-rise buildings are poorly understood. For example, it is not clear how basements of different sizes affect how the ground shakes these buildings. Recent earthquakes have damaged groups of buildings in cities, but it is difficult to learn from these observations due to the lack of documentation of the ground motion and building performance. However, a comprehensive program of realistic scaled centrifuge experiments, where the input motion, ground conditions, ground response, and structural response can be carefully tracked, followed by back-analyses of these model tests, can be employed to enhance the profession?s understanding of SSI effects of buildings in a dense urban environment. The unique capabilities of the NEES UC Davis centrifuge will be used to advance our understanding of SSI effects for clusters of buildings so that reliable assessments can be made. In a centrifuge, a box containing soil and model buildings is spun at a rotational acceleration of 50 g so that a 2 foot thickness of soil has the same stresses as a 100 foot thickness of soil. Building models are scaled similarly so realistic responses are measured in these experiments. The testing program will develop a database of well-documented model ?case histories? of building performance within a dense urban environment at sites undergoing moderate and severe ground shaking with and without ground failure. Researchers can then use these experimental results to advance our understanding of these phenomena and our ability to analyze them. Physical experiments followed by numerical simulations will allow us to develop guidance for designers and policy makers on how clusters of buildings perform during earthquakes. This project will advance fundamental science and knowledge in engineering with substantial intellectual benefits to both geotechnical and structural engineering disciplines. Both disciplines will contribute to and benefit from the development and deployment of an integrated performance-based seismic design and a robust loss-estimation methodology. The project will also train Ph.D. students, bring in undergraduate students from a teaching university, engage under-represented students, impact building code development and performance-based seismic design, and outreach to a broad spectrum of end-users by emphasizing web-accessed media. We will also translate the challenge of solving this realistic problem to undergraduates (and others) via a ?Shaking of a City Block? shaking table competition to have students consider the effects of adjacent structures and soil on seismic performance. Data from this project will be made available through the NEES data repository (http://www.nees.org).