BRIGE: Damage Evaluation and Life-Cycle Assessment of Reinforced HPFRC Beam-Column Joints under Multi-Axial Loading

BRIGE：多轴荷载下加固 HPFRC 梁柱节点的损伤评估和生命周期评估

• 批准号: 1342160
• 负责人: Bora Gencturk
• 金额: $ 17.46万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1342160&HistoricalAwards=false
• 关键词: BRIGE; Damage; Evaluation; Life; Cycle

Technical DescriptionDespite significant advances in structural materials, catastrophic beam-column joint failures in reinforced concrete (RC) buildings persist in being a problem during earthquakes. The behavior and failure mechanisms in RC joints have been extensively studied in the past and are well understood under simple (planar) loading conditions. Current practice tells us to increase the joint dimensions or the amount of reinforcing steel to enhance the capacity of the joints and prevent premature failure. However, this approach is definitely not sustainable. Additionally, as observed in recent earthquakes, this practice does not always prevent catastrophic failures in the joint region, leading to the conclusion that the behavior of joints under complex (multi-axial) loading conditions is still not well understood.In this project, high-performance fiber reinforced concrete (HPFRC) will be selectively used at the beam-column joints to improve the structural performance of buildings while keeping the additional costs at a minimum. Using experimental and computational methods, a comparative damage evaluation and life-cycle cost assessment of building with RC and HPFRC joints will be conducted. Analysis of joints is a difficult task because of the complex load transfer and the behavior of materials under multi-axial loading. Therefore, two multi-axial (6 degree-of-freedom) loading units will be used to impose realistic loading and boundary conditions on the joints, and a digital-image correlation system for non-contact deformation measurements (DIC) will be used to obtain full-field 3-D strain maps to study critical deformation states that lead to the initiation of damage as well as its progression until complete failure. These research activities are anticipated to yield critical new knowledge and understanding of the behavior of RC and R-HPFRC joints, and reliable computational tools to study the RC/reinforced-HPFRC material and joint behavior.Broader Significance and ImportanceThe proposed novel approach is expected to transform the design and construction of RC beam-column joints over the long-term. A direct benefit of this project to society is the improvement in public safety in response to earthquakes. An additional benefit is increased sustainability in the form of reduced direct and indirect economic losses and environmental impacts. The achievements in this project will be a large step in reaching the ultimate goal of resilient and sustainable civil infrastructures. The proposed joint concept also has broad applicability in other types of concrete construction, including offshore and nuclear structures. The data collected from these novel testing and measurement approaches will serve as benchmarks for the development of new theories for numerical modeling and engineering simulations, which could not be considered previously because of the lack of supporting experimental data.Broadening Participation ActivitiesThe University of Houston (UH) is a Hispanic-Serving Institution. The UH student body of nearly 40,000 students is one of the most diverse in the United States. Educational modules will be developed and introduced in three courses to influence the education of more than 100 students per year. Because of the inherent campus diversity, these educational initiatives will naturally reach a diverse audience. Graduate and undergraduate students will be recruited from underrepresented groups. In collaboration with a local high school with more than 90% underrepresented students, a field trip will be organized every year for 25 students to visit the UH campus and participate in hands-on training. In addition, one high school teacher will be recruited every summer to gain exposure to research activities and help develop a course module for high school physics courses. Through the developed education activities, high school teachers, high school students, and undergraduate and graduate students will have an opportunity to interact and learn from each other. The course modules will directly derive from the research findings and be implemented in high school and college level courses, thereby naturally integrating research and education.This research has been funded through the Broadening Participation Research Initiation Grants in Engineering solicitation, which is part of the Broadening Participation in Engineering Program of the Engineering Education and Centers Division.

技术说明尽管结构材料取得了重大进展，但钢筋混凝土（RC）建筑物中的灾难性梁柱接头失效仍然是地震期间的一个问题。在过去，钢筋混凝土节点的性能和破坏机制已经得到了广泛的研究，并在简单（平面）加载条件下得到了很好的理解。目前的做法告诉我们，增加接头尺寸或钢筋的数量，以提高接头的能力，防止过早失效。但是，这种做法肯定是不可持续的。此外，正如在最近的地震中所观察到的那样，这种做法并不总是能防止接缝区域的灾难性破坏，从而得出结论，复杂条件下的接缝性能（多轴）加载条件仍然没有得到很好的理解。在本项目中，高性能纤维增强混凝土（HPFRC）将有选择地用于梁-柱接头，以提高建筑物的结构性能，同时保持在最低限度的额外成本。采用试验和计算方法，对钢筋混凝土和高强钢纤维混凝土节点的建筑物进行比较损伤评估和寿命周期成本评估。由于节点复杂的荷载传递和材料在多轴荷载作用下的行为，节点分析是一项困难的任务。因此，将使用两个多轴（6自由度）加载装置对接头施加真实的载荷和边界条件，并使用非接触式变形测量（DIC）的数字图像相关系统获得全场3-D应变图，以研究导致损伤开始的临界变形状态及其进展，直至完全失效。这些研究活动预计将产生关键的新知识和理解的行为的RC和R-HPFRC节点，和可靠的计算工具来研究的RC/crossed-HPFRC材料和联合behaviors.Broader的意义和ImportanceThe提出的新方法预计将改变设计和施工的RC梁柱节点在长期。该项目对社会的直接好处是改善了应对地震的公共安全。另一个好处是可持续性得到提高，减少了直接和间接的经济损失和环境影响。该项目的成就将是实现具有复原力和可持续的民用基础设施这一最终目标的一大步。所提出的接头概念在其他类型的混凝土结构中也具有广泛的适用性，包括海上和核结构。从这些新的测试和测量方法收集的数据将作为基准的数值建模和工程模拟的新理论的发展，这不能被认为是以前，因为缺乏支持的实验数据。扩大参与活动休斯顿大学（UH）是一个西班牙裔服务机构。近40，000名学生的UH学生团体是美国最多样化的学生之一。将在三门课程中开发和引入教育模块，每年影响100多名学生的教育。由于固有的校园多样性，这些教育举措将自然达到不同的观众。研究生和本科生将从代表性不足的群体中招募。在与当地高中合作，超过90%的学生代表不足，实地考察将每年组织25名学生参观UH校园，并参加动手培训。此外，每年夏天将招聘一名高中教师，以接触研究活动，并帮助开发高中物理课程的课程模块。通过开展的教育活动，高中教师、高中学生、本科生和研究生将有机会相互交流和学习。课程模块将直接从研究成果中衍生出来，并在高中和大学水平的课程中实施，从而自然地将研究和教育结合起来。这项研究已经通过扩大参与工程研究启动赠款征集获得资助，这是工程教育和中心部门扩大参与工程计划的一部分。