NEESR: Reserve Capacity in New and Existing Low-Ductility Steel Braced Frames

NEESR：新的和现有的低延展性钢支撑框架的储备能力

• 批准号: 1207976
• 负责人: Larry Fahnestock
• 金额: $ 71.65万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-10-01 至 2017-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1207976&HistoricalAwards=false
• 关键词: NEESR; Reserve; Capacity; New; Existing

This award aims to understand and characterize, at a fundamental level, the influence of reserve capacity on the seismic performance of low-ductility steel concentrically-braced frames up to the point of collapse. Although low-ductility steel braced frames have brittle brace elements and connections, they can achieve system ductility if their gravity framing and gusset plate connections act partially-restrained after braces fracture. These partially-restrained connections form a "reserve" moment frame system that can prevent sidesway collapse even when the primary lateral force resisting system is significantly damaged. Design provisions for steel structures in low and moderate seismic regions implicitly rely on reserve capacity for collapse prevention, even though the nature of this reserve capacity is not well-understood and can vary widely. Thus, there is an essential need for clarity and consistency in considering reserve capacity for seismic design in moderate seismic regions. Foundational understanding of reserve capacity will provide broad national benefit by establishing an economical and reliable framework for design of new buildings in low and moderate seismic regions and for evaluation of existing buildings in all seismic regions of the United States. These significant contributions will be accomplished through integration of large-scale testing, design studies, computational simulations, and reliability-based performance assessments. The research team from the University of Illinois at Urbana-Champaign and Tufts University will use the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) facilities at Lehigh University. Collaboration with complementary research being conducted at Ecole Polytechnique Montreal will provide valuable synergistic opportunities and enhance the research impact. Data from this project will be archived and made available to the public through the NEES Project Warehouse/data repository (http://www.nees.org).The philosophy and application of system reserve capacity developed out of this research will open new possibilities for designing and assessing structures in all seismic regions, with special importance for moderate seismic regions, renovation in high seismic regions, and the design of special structures. Engineers will have simple yet effective tools for rationally designing and assessing low-ductility structures using reserve capacity to prevent seismic collapse. This philosophy of reserve capacity, which prioritizes cost reduction over achieving optimum levels of ductility, can also significantly impact design in developing countries where the seismic details that have become standards in the United States are not affordable or achievable with available technology. While this work focuses on steel structures, the scope of reserve capacity is much broader and more general. Once understood in the context of steel, reserve capacity may also find uses in other materials and systems both in the United States and abroad. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).

该奖项旨在从根本上理解和表征储备能力对低延展性钢同心支撑框架直至倒塌点的抗震性能的影响。尽管低延展性钢支撑框架具有脆性支撑元件和连接，但如果其重力框架和角撑板连接在支撑断裂后起到部分约束作用，则它们可以实现系统延展性。这些部分约束的连接形成“储备”力矩框架系统，即使主要抗侧向力系统严重损坏，也可以防止侧向倒塌。 低度和中度地震地区钢结构的设计规定隐含地依赖于防止倒塌的储备能力，尽管这种储备能力的性质尚不清楚并且可能存在很大差异。 因此，在考虑中度地震区抗震设计储备能力时，必须具有明确性和一致性。 对储备能力的基本了解将为低度和中度地震地区的新建筑设计以及美国所有地震地区现有建筑的评估建立经济可靠的框架，从而提供广泛的国家利益。 这些重大贡献将通过大规模测试、设计研究、计算模拟和基于可靠性的性能评估的整合来实现。 来自伊利诺伊大学厄巴纳-香槟分校和塔夫茨大学的研究团队将使用里哈伊大学的小乔治·布朗网络地震工程模拟 (NEES) 设施。 与蒙特利尔理工学院正在进行的补充研究合作将提供宝贵的协同机会并增强研究影响。 该项目的数据将被存档并通过 NEES 项目仓库/数据存储库 (http://www.nees.org) 向公众开放。本研究开发的系统储备容量的理念和应用将开启新的可能性适用于所有地震区的结构设计和评估，特别重要的是中度地震区、高地震区的改造以及特殊结构的设计。 工程师将拥有简单而有效的工具，利用储备能力来合理设计和评估低延展性结构，以防止地震倒塌。这种储备能力的理念，优先考虑降低成本而不是实现最佳的延展性水平，也会对发展中国家的设计产生重大影响，在这些国家，美国已成为标准的抗震细节是无法负担或通过现有技术实现的。 虽然这项工作的重点是钢结构，但储备能力的范围更广泛、更普遍。 一旦在钢铁的背景下得到理解，储备能力也可能在美国和国外的其他材料和系统中找到用途。 该奖项是国家地震减灾计划（NEHRP）的一部分。