NEESR-CR: Unbonded Post-Tensioned Rocking Walls for Seismic Resilient Structures

NEESR-CR：用于抗震结构的无粘结后张法摇墙

• 批准号: 1041650
• 负责人: Sri Sritharan
• 金额: $ 119.99万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-12-01 至 2015-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1041650&HistoricalAwards=false
• 关键词: NEESR; CR; Unbonded; Post; Tensioned

This award is an outcome of the NSF 09-524 program solicitation "George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)" competition and includes Iowa State University (ISU) as well as two University of Minnesota campuses: Twin Cities (UMN) and Duluth (UMD). This project will utilize the NEES facilities located at UMN and the University of Nevada at Reno.The motivation for this research is that damage caused by earthquakes, and the subsequent economic losses, underscore the need to focus on developing earthquake resilient buildings. One method of achieving resilient buildings is to design them with self-centering structural systems to resist earthquake lateral loads. Using unbonded post-tensioning tendons, a cost-effective, self-centering wall system known as PreWEC (i.e., Precast Wall with two End Columns) was developed at ISU, which has been proven analytically and experimentally to have excellent seismic performance with minimal structural damage. In this system, as well as in single rocking walls (SRWs) designed with unbonded post-tensioning, the response is dominated by a rocking mode. However, the energy loss caused by the wall impacting the foundation during rocking has not been given consideration in design due to lack of knowledge on this subject. Significant evidence suggests that this mechanism alone may be sufficient to dissipate the seismic energy. Furthermore, the resilience of a building containing rocking walls is also dependent on the behavior of surrounding structural components, especially floors and gravity columns, and their interactions with the seismic resistant systems. To ensure a fully resilient structure, these interactions should be addressed by understanding the wall-floor connection responses. Intellectual Merit: In collaboration with E-Defense in Japan and researchers at the University of Auckland in New Zealand, the intellectual merit of this project is the development of seismic resilient building solutions utilizing the fundamental characteristics of seismic rocking of both SRWs and PreWECs. By involving an international, cross-disciplinary team of experts and two NEES facilities, the project will accomplish this goal by completing the following objectives: 1) understand the fundamental characteristics of seismic rocking of self-centering walls through NEES/international tests, thereby identifying different energy dissipation sources (i.e., energy loss due to impact, viscous damping and hysteretic damping); 2) develop suitable connections between rocking walls and floors, and quantify the wall-floor-column interactions using large-scale tests; 3) ensure safety of the rocking systems through sufficient anchorage of the unbonded tendons; 4) design seismic resilient structures; 5) improve numerical simulation of buildings designed with rocking walls and different floor systems; 6) formulate design guidelines; and 7) educate students, practitioners, and others (e.g., policymakers) on the significance of the proposed study.Broader Impacts: This award also has several broader impacts. First, it offers several unique opportunities for graduate and undergraduate students from diverse populations to participate and collaborate with an international team of researchers in a distributed NEES environment. Second, it promotes the participation of underrepresented students in civil engineering and introduces K-12 students to the new NEES collaboration model and benefits of rocking walls in seismic resistant design. The research team will contribute to Project Lead the Way (PLTW), a program designed to prepare middle and high school students for college-level engineering education by exposing them to engineering courses. UMD will pilot the proposed PLTW program at schools in northern Minnesota, including tribal schools. Next, a unique, team-oriented course module will be developed by integrating the research outcomes so that it can be used for instruction at the graduate and undergraduate levels. This module will be made available to the earthquake engineering community through NEEShub. Using the planned NEES collaboration within the project, the project team will also contribute to advancing NEES telepresence technologies. Finally, the proposed project will enhance research and education at the three participating institutions, which includes a predominantly undergraduate university. All anticipated project outcomes will ultimately produce new basic knowledge needed to design safer, more resilient buildings in seismic regions and thus contribute to seismic hazard mitigation in the United States and around the world. Data from this project will be archived and made available to the public through the NEES data repository. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).

该奖项是 NSF 09-524 计划征集“George E. Brown, Jr. 地震工程模拟 (NEES) 研究网络 (NEESR)”竞赛的结果，包括爱荷华州立大学 (ISU) 以及两所明尼苏达大学校区：双城校区（UMN）和德卢斯校区（UMD）。该项目将利用位于 UMN 和内华达大学里诺分校的 NEES 设施。这项研究的动机是地震造成的破坏以及随后的经济损失强调需要重点开发抗震建筑。 实现弹性建筑的一种方法是设计具有自定心结构系统的建筑，以抵抗地震横向荷载。 ISU 使用无粘结的后张预应力筋，开发了一种经济高效的自定心墙系统，称为 PreWEC（即带有两个端柱的预制墙），该系统已被分析和实验证明具有优异的抗震性能，且结构简单损害。在该系统以及采用无粘结后张法设计的单摇墙 (SRW) 中，响应主要由摇动模式决定。然而，由于缺乏这方面的认识，设计中并未考虑摇动过程中墙体撞击基础所造成的能量损失。 重要证据表明，仅此机制就足以消散地震能量。此外，包含摇墙的建筑物的弹性还取决于周围结构部件的行为，特别是地板和重力柱，以及它们与抗震系统的相互作用。为了确保结构具有完全的弹性，应通过了解墙-地板连接响应来解决这些相互作用。智力优势：该项目与日本 E-Defense 和新西兰奥克兰大学的研究人员合作，其智力优势是利用 SRW 和 PreWEC 的地震摇动基本特征开发抗震建筑解决方案。通过国际跨学科专家团队和两个 NEES 设施的参与，该项目将通过完成以下目标来实现这一目标：1）通过 NEES/国际测试了解自定心墙地震摇动的基本特征，从而确定不同的能量耗散源（即由于冲击、粘性阻尼和迟滞阻尼造成的能量损失）； 2）在摇动墙和地板之间建立适当的连接，并通过大规模测试量化墙-地板-柱的相互作用； 3）通过对无粘结筋腱进行充分的锚固，确保摇摆系统的安全； 4）设计抗震结构； 5) 改进采用摇墙和不同楼板系统设计的建筑物的数值模拟； 6）制定设计指南； 7) 教育学生、从业者和其他人（例如政策制定者）​​了解拟议研究的重要性。 更广泛的影响：该奖项还具有一些更广泛的影响。首先，它为来自不同人群的研究生和本科生提供了一些独特的机会，让他们在分布式 NEES 环境中参与国际研究团队并与之合作。其次，它促进了土木工程领域代表性不足的学生的参与，并向 K-12 学生介绍了新的 NEES 协作模式以及摇墙在抗震设计中的优势。 该研究团队将为 Project Lead the Way (PLTW) 项目做出贡献，该项目旨在通过让中学生和高中生接触工程课程，为他们接受大学水平的工程教育做好准备。 UMD 将在明尼苏达州北部的学校（包括部落学校）试行拟议的 PLTW 计划。接下来，将整合研究成果，开发独特的、以团队为导向的课程模块，以便用于研究生和本科生的教学。该模块将通过 NEEShub 提供给地震工程界。利用项目内计划的 NEES 协作，项目团队还将为推进 NEES 远程呈现技术做出贡献。最后，拟议的项目将加强三个参与机构（其中包括一所以本科为主的大学）的研究和教育。 所有预期的项目成果最终将产生在地震区设计更安全、更具弹性的建筑所需的新基础知识，从而为美国和世界各地的地震灾害减轻做出贡献。 该项目的数据将被存档并通过 NEES 数据存储库向公众开放。 该奖项是国家地震减灾计划（NEHRP）的一部分。