NEESR: Collaborative Developments for Seismic Rehabilitation of Vulnerable Braced Frames

NEESR：易损支撑框架抗震修复的协作开发

• 批准号: 1208002
• 负责人: Charles Roeder
• 金额: $ 100万
• 依托单位: University of Washington
• 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: 2012-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1208002&HistoricalAwards=false
• 关键词: NEESR; Collaborative; Developments; Seismic; Rehabilitation

Steel concentrically braced frames (CBFs) are stiff and strong, making them efficient seismic load resisting systems. Modern CBF seismic design was initiated with significant code changes in 1988 and is differentiated from older CBFs (classified as non-seismic CBFs or NCBFs) because NCBFs were designed without consideration of the brace behavior or capacity-design principles. In regions of high seismicity, thousands of NCBFs remain in service. In regions of low and moderate seismicity, these systems are still being constructed. A cursory review of the NCBF inventory indicates that braces and connections vary, and there is a large potential for unwanted and brittle response modes. Research into these systems is largely absent from the literature. Taken together, these systems are both widespread and unpredictable, making this category of lateral force resisting system a critical seismic hazard. This research project will advance evaluation and rehabilitation of NCBFs. Large-scale experimentation will be conducted using the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) facility at the University of California, Berkeley, to simulate existing and rehabilitated multi-story NCBFs. The experimental results will provide high-resolution data to support nonlinear simulation of NCBFs. The integration of the experiments and simulations will provide key information about the system performance, identify vulnerabilities, and inform the retrofit requirements. The identified deficiencies will be addressed through retrofit schemes based on innovative rehabilitation strategies investigated in prior NSF-supported NEES research projects, whose data is available through the NEES Project Warehouse/data repository (http://www.nees.org). Retrofit categories slated for study include use of innovative braces and bracing systems, column uplift and rocking, and connection designs balanced with the replaced and existing components. These strategies will be integrated with the existing frames in the second phase of the large-scale, integrated multi-story testing, with the design informed from nonlinear analytical simulation and archived NEES Project Warehouse data. The final phase of the experimentation will study a full building using advanced hybrid simulation. In older construction, the seismic response may depend more heavily on the gravity frames. This culminating experiment will study a partially retrofitted NCBF building which may be an economical option to meet a collapse prevention performance objective in many cases; the non-retrofitted NCBFs are simulated in the computer and the retrofitted NCBFs and gravity frames are simulated experimentally. The research will result in unique data to support the evaluation and retrofit of these seismically vulnerable systems. This award is a collaboration among researchers from the University of Washington, University of California, Berkeley, National Taiwan University, and the American Institute of Steel Construction. Data from this project will be archived and made available to the public through the NEES Project Warehouse/data repository.As a whole, the research results will transform the understanding of and facilitate rehabilitation strategies for NCBFs. The results will provide important findings to validate and advance engineering approaches for NCBF evaluation and rehabilitation. Specific tools that will be developed using the research data include acceptance criteria, backbone curves, and collapse margin ratios for both NCBFs and retrofitted NCBFs. The project will also advance student learning and exposure through the research process. High school students from underrepresented groups will be selected for summer research internships to aid in the experimental research in collaboration with the Seattle Mathematics, Engineering and Science Achievement program. The research results will also be integrated into the senior level curriculum, using a senior-level cross-class project on seismic evaluation and retrofit of a NCBF building as the central learning tool. Analysis of the building will be conducted in the senior-level structural analysis class. Analysis of the individual components will be the focus of the project in the structural steel design class. The retrofitted system will be designed in the capstone design class, taught in the spring of the students' senior year. Technology transfer will be achieved through webinars and a diverse industry coalition who will help disseminate results. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).

钢结构中心支撑框架结构既坚固又坚固，是一种高效的抗震体系。现代CBF抗震设计始于1988年，规范进行了重大修改，与旧的CBF(分类为非抗震CBF或NCBF)有所不同，因为NCBF在设计时没有考虑支撑性能或能力设计原则。在高地震活动地区，数以千计的NCBF仍在使用中。在中低地震活动区，这些系统仍在建设中。粗略审查NCBF清单表明，支撑和连接各不相同，很可能出现不需要的和脆弱的响应模式。对这些系统的研究在很大程度上没有出现在文献中。综上所述，这些体系既广泛又不可预测，使这类侧向力抵抗体系成为关键的地震危险。这一研究项目将推动对非政府合作伙伴关系的评估和修复。将使用小乔治·E·布朗进行大规模实验。加州大学伯克利分校地震工程模拟网络(NEES)设施，用于模拟现有和修复的多层NCBF。实验结果将为NCBF的非线性模拟提供高分辨率数据支持。实验和模拟的集成将提供有关系统性能的关键信息，识别漏洞，并告知改造要求。已确定的缺陷将通过基于先前国家科学基金会支持的新能源研究项目中调查的创新康复战略的改造计划来解决，其数据可通过新能源研究项目仓库/数据储存库(http://www.nees.org).)获得计划研究的翻新类别包括使用创新的支撑和支撑系统，柱子提升和摇动，以及与更换的和现有的部件保持平衡的连接设计。这些战略将在大规模综合多层试验的第二阶段与现有框架相结合，设计依据是非线性分析模拟和NEES项目仓库存档数据。实验的最后阶段将使用先进的混合模拟来研究一座完整的建筑。在较老的建筑中，地震反应可能更多地依赖于重力框架。本试验将研究部分加装的NCBF建筑，这在许多情况下可能是满足防倒塌性能目标的经济选择；在计算机中对未加装的NCBF进行模拟，并对加装的NCBF和重力框架进行实验模拟。这项研究将产生独特的数据，以支持对这些地震易损性系统的评估和改造。该奖项是华盛顿大学、加州大学伯克利分校、国立台湾大学和美国钢铁建筑学会的研究人员合作的。该项目的数据将被存档，并通过NEES项目仓库/数据储存库向公众提供。作为一个整体，研究成果将改变人们对NCBF康复战略的理解，并促进这些战略。研究结果将为验证和推进NCBF评估和康复的工程方法提供重要的发现。将利用研究数据开发的具体工具包括NCBF和改造后的NCBF的验收标准、主干曲线和崩溃边际比率。该项目还将通过研究过程促进学生的学习和接触。来自代表性不足群体的高中生将被选入暑期研究实习，与西雅图数学、工程和科学成就计划合作，帮助进行实验研究。研究成果还将被纳入高级课程，使用关于NCBF大楼抗震评估和翻新的高级跨班级项目作为中心学习工具。建筑物的分析将在高级结构分析课上进行。对单个部件的分析将是结构钢设计课程中项目的重点。改装后的系统将在顶石设计课程中设计，该课程将在学生高年级的春季教授。将通过网络研讨会和将帮助传播成果的不同行业联盟实现技术转让。该奖项是国家减少地震灾害计划(NEHRP)的一部分。