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

该奖项旨在从根本上理解和描述储备能力对低延性钢中心支撑框架直到倒塌时抗震性能的影响。虽然低延性钢支撑框架具有脆性的支撑构件和节点，但如果其重力框架和节点板节点在支撑断裂后起到部分约束的作用，则可以实现体系的延性。这些部分约束的连接形成了一个“储备”的弯矩框架体系，即使在主要的抗侧力体系遭到严重破坏的情况下，也可以防止侧移倒塌。低地震区和中等地震区钢结构的设计规定隐含地依赖于储备能力来防止坍塌，尽管这种储备能力的性质还没有得到很好的理解，而且差异很大。因此，在考虑中等地震区的抗震设计储备能力时，有必要明确和一致。对储备能力的基本了解将为美国所有地震区的新建筑设计和现有建筑评估建立一个经济可靠的框架，从而为国家带来广泛的利益。这些重大贡献将通过整合大规模测试、设计研究、计算模拟和基于可靠性的性能评估来实现。来自伊利诺伊大学香槟分校和塔夫茨大学的研究小组将使用小乔治·E·布朗。利哈伊大学地震工程模拟(NEES)设施网络。与蒙特利尔理工学院正在进行的补充研究的协作将提供宝贵的协同机会，并加强研究的影响。该项目的数据将被存档，并通过NEES项目仓库/数据储存库(http://www.nees.org).The)向公众提供(这项研究提出的系统储备能力的理念和应用将为所有地震区的结构设计和评估开辟新的可能性，特别是对中等地震区、高地震区的翻新和特殊结构的设计。工程师们将拥有简单而有效的工具，利用储备能力合理设计和评估低延性结构，以防止地震倒塌。这种储备能力的理念将降低成本置于实现最佳延展性水平之上，这也会对发展中国家的设计产生重大影响，在这些国家，抗震细节已经成为美国的标准，但现有技术无法负担或实现这些细节。虽然这项工作的重点是钢结构，但储备能力的范围要广泛得多，也更一般。一旦在钢铁的背景下理解，储备产能也可能在美国和国外的其他材料和系统中找到用途。该奖项是国家减少地震灾害计划(NEHRP)的一部分。

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).