Advancing Knowledge on the Performance of Seismic Collectors in Steel Building Structures

增进对钢建筑结构地震采集器性能的了解

• 批准号: 1662816
• 负责人: Robert Fleischman
• 金额: $ 79.8万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1662816&HistoricalAwards=false
• 关键词: Advancing; Knowledge; Performance; Seismic; Collectors

To safely survive an earthquake, and thereby protect its occupants, contents, adjacent property, and passersby, a building structure must transfer the large forces that develop during the earthquake from within the building down to the foundation. Earthquake (lateral) forces are generated by the building weight being accelerated horizontally, and thus most earthquake forces originate in the building's heaviest element, i.e., its floors. A key structural element in the force transfer path to the foundation are collectors, which are either special reinforcement in the floor slab or special beams below the slab, that "collect" the forces in the floor, and transfer them to the primary seismic force-resisting vertical elements (frames, braces, or walls). The loss of collectors or collector connections can be catastrophic, as evidenced by the collapse of the CTV building in the 2011 Christchurch, New Zealand earthquake, which killed 115 people, the largest loss of life in this event, and to some extent the collapse of nine parking garages in the 1994 Northridge, California earthquake. Despite the critical nature of seismic collectors, no research effort, including physical testing, has focused specifically on collectors, and knowledge of their seismic performance is lacking. A challenge in understanding the performance of seismic collectors is the complex nature of the floor system itself, a complicated assemblage of many components of different materials (e.g., steel, metal, and concrete) at different elevations, with multiple purposes and uncertain force paths. Past seismic design methodologies for buildings may have significantly underestimated the collector forces. This lack of knowledge impacts not only new construction but also the assessment and retrofit of existing, especially critical care, facilities in high seismic regions. This condition also applies to older non-seismic compliant steel structures nationwide, where inadequate or non-existent seismic collectors are often a major concern. A better understanding of the performance of steel seismic collectors is needed for safe and economical structures, both in the existing building stock and for new construction. Further, the collector's unique role as the critical link between the floor and the vertical elements provides an opportunity for collectors from trying to "out-strength" the earthquake force to instead serve as an innovative force-limiting element that protects the structure from damage. The goals of this research are to: (1) advance knowledge on the seismic performance, analysis, and design of collectors in steel composite floor systems, and (2) develop new knowledge on the reliable seismic performance and potential benefits of innovative collector concepts that can lead to low-damage structural design. This project will support researchers and graduate students from the University of Arizona, University of California, San Diego, and Lehigh University. The project will benefit from working closely with collaborators who are separately supported, i.e., a researcher and a practitioner in New Zealand and an industry panel of seismic design engineers in the United States. An outreach program will be conducted by the University of Arizona with local K-8 schools identified demographically as possessing student bodies of predominately underrepresented groups. The outreach program will target third, fourth, and eighth grade students to include: (1) slides shows and question and answer sessions on earthquake engineering, (2) career mentoring from graduate and undergraduate students, and (3) hands-on science and math activities.In this project, an integrated research program will investigate the performance of seismic collectors for steel composite deck structures using the experimental and computational simulation capabilities afforded by the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI). The research will involve: (1) large-scale testing of collector elements in a steel composite floor system at the NHERI experimental facility at Lehigh University, (2) shake table testing of a 0.4-scale, single-story, steel composite floor system at the NHERI shake table facility at the University of California, San Diego, and (3) nonlinear analysis of steel structure collector elements, details and surrounding regions under seismic effects, and earthquake simulations of steel buildings under strong earthquakes. The planned experiments on steel collectors, with realistic boundary conditions and inertial forces, will be the first of its kind. New data products and calibrated numerical models will be produced from large-scale physical testing. Analytical models will be developed for the collectors and the collector inertial force paths. Transfer of research results into practice will include: (1) new concepts for low-damage structural design, (2) research-based design recommendations, and (3) assessment and retrofit guidelines.

为了在地震中安全生存，从而保护其居住者、内容物、邻近的财产和路人，建筑物结构必须将地震中产生的巨大力量从建筑物内部转移到地基上。地震（横向）力是由建筑物重量水平加速产生的，因此大多数地震力来自建筑物最重的部分，即楼层。在将力传递到基础的路径中，一个关键的结构元件是集热器，它要么是楼板上的特殊钢筋，要么是楼板下面的特殊梁，它“收集”楼板上的力，并将它们传递给主要的抗震垂直元件（框架、支撑或墙壁）。收藏家或收藏家连接的损失可能是灾难性的，2011年新西兰基督城地震中CTV大楼的倒塌证明了这一点，造成115人死亡，这是该事件中最大的生命损失，从某种程度上说，1994年加州北岭地震中9个停车场的倒塌也证明了这一点。尽管地震集热器具有至关重要的性质，但没有研究工作，包括物理测试，专门针对集热器，并且缺乏对其地震性能的了解。了解地震收集器性能的一个挑战是地板系统本身的复杂性，它是不同高度的不同材料（例如钢、金属和混凝土）的许多组件的复杂组合，具有多种用途和不确定的力路径。过去的建筑抗震设计方法可能大大低估了集热器的作用力。这种知识的缺乏不仅影响了新建筑，也影响了高震区现有设施，特别是重症监护设施的评估和改造。这一条件也适用于全国范围内的老式非抗震钢结构，在这些地方，不充分或不存在地震收集器往往是一个主要问题。无论是现有建筑还是新建建筑，都需要更好地了解钢抗震集热器的性能，以保证结构的安全和经济。此外，集热器作为地板和垂直构件之间的关键纽带的独特作用，为集热器提供了一个尝试“超越”地震力的机会，而不是作为一个创新的力限制元件，保护结构免受破坏。本研究的目标是：(1)提高对钢组合楼板系统中集热器的抗震性能、分析和设计的认识；(2)开发关于可靠的抗震性能和创新集热器概念的潜在效益的新知识，这些概念可以导致低损伤结构设计。该项目将支持来自亚利桑那大学、加州大学圣地亚哥分校和利哈伊大学的研究人员和研究生。该项目将受益于与单独支持的合作者密切合作，即新西兰的研究人员和实践者以及美国的地震设计工程师行业小组。亚利桑那大学将与当地的K-8学校开展一项推广计划，这些学校在人口统计学上被认定拥有占主导地位的弱势群体的学生团体。外展计划将针对三年级，四年级和八年级的学生，包括：(1)关于地震工程的幻灯片展示和问答环节，(2)研究生和本科生的职业指导，(3)动手科学和数学活动。在这个项目中，一个综合研究计划将利用由nsf支持的自然灾害工程研究基础设施（NHERI）提供的实验和计算模拟能力，研究钢复合甲板结构的地震收集器的性能。研究将涉及：(1)在Lehigh University的NHERI实验设施中对钢组合楼板系统中的集热元件进行了大规模测试；(2)在加州大学圣地亚哥分校的NHERI振动台设施中对0.4尺度单层钢组合楼板系统进行了振动台测试；(3)对地震作用下钢结构集热元件、细部和周围区域的非线性分析，以及钢结构建筑在强震作用下的地震模拟。计划在具有现实边界条件和惯性力的钢收集器上进行的实验将是同类实验中的第一次。大规模物理试验将产生新的数据产品和校准的数值模型。将建立集热器和集热器惯性力路径的分析模型。将研究成果转化为实践将包括：(1)低损伤结构设计的新概念，(2)基于研究的设计建议，以及(3)评估和改造指南。