Bond Stress-Slip of Reinforcing Bars and Prestressing Strands in HPFRC Composites

HPFRC 复合材料中钢筋和预应力绞线的粘结应力滑移

• 批准号: 0408623
• 负责人: Antoine Naaman
• 金额: --
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2008-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0408623&HistoricalAwards=false
• 关键词: Bond; Stress; Slip; Reinforcing; Bars

High quality bond between the concrete matrix and reinforcing bars or prestressing tendons is vital for reliable structural behavior. Recent advances in micro-mechanics design and tailoring of fiber reinforced cement composites (FRCCs) allow us to obtain high-performance composites (HPFRCCs) with strain-hardening response in tension using less than 2% fibers by volume. In effect, this opens the way to a whole range of practical structural applications including on site construction and precast products. The main objective of this research is to study the fundamental mechanisms that control the bond stress versus slip response of reinforcing bars and prestressing strands embedded in HPFRCCs under both monotonic and cyclic loading. The bond-stress versus slip relationship is a constitutive property of the interface between reinforcement and concrete and allows the estimation of bar development length and strand transfer length in reinforced and prestressed concrete structures. While providing a better solution for numerous current designs, this proposal also opens the way to the next generation of infrastructure where fiber reinforced concrete will be considered a readily available alternative in structural applications.The experimental program is aimed at generating the necessary information to understand the interaction between steel rebars or prestressing strands and HPFRCC materials under monotonic and reversed cyclic loading conditions. The main objective of the analytical study is to formulate bond-stress versus slip models for reinforcing bars and prestressing strands based on the main mechanisms observed in the experiments, and from the test results obtained. Based on the findings, recommendations will be made to modify the current development length, splice length, and transfer length equations given in the ACI code for reinforcing bars and prestressing strands, or new equations will be proposed if needed.The global building industry faces a growing need for advanced materials to address increasing complexity, more stringent code requirements, demand for longer service life, needs to reduce repair-rehabilitation-maintenance cost, and escalating security and protection requirements. This research addresses the above needs by making the use of high performance fiber reinforced concrete readily possible; this will allow the development of new structural concepts, and offers the means to improve the performance of existing designs. In the area of education, emphasis will be placed on attracting undergraduate students, especially women and minorities by working with the Society of Women Engineers and the Minority Engineering Program Office of the University of Michigan. A website, dedicated to this research, will be developed and will contain pertinent information related to the experimental and analytical studies, as well as the course material. Overall, this research will add to the knowledge base, and will expose students to the use of advanced materials in structural applications.

混凝土基质与加固条或预应力肌腱之间的高质量键对可靠的结构行为至关重要。微型力学设计和纤维增强水泥复合材料（FRCC）的最新进展使我们能够获得高性能复合材料（HPFRCC），并使用少于2％的纤维（按体积）使用小于2％的纤维来获得张力的应变响应。实际上，这为包括现场构建和预制产品在内的一系列实用结构应用开辟了道路。这项研究的主要目的是研究控制键应力与加固条和嵌入HPFRCC的预应力链的基本机制，并在单调和环状载荷下嵌入HPFRCC。粘合应力与滑移关系是钢筋和混凝土之间界面的组成性特性，可以估计条形发育长度和钢筋和预应力混凝土结构中的链发育长度和链的转移长度。 While providing a better solution for numerous current designs, this proposal also opens the way to the next generation of infrastructure where fiber reinforced concrete will be considered a readily available alternative in structural applications.The experimental program is aimed at generating the necessary information to understand the interaction between steel rebars or prestressing strands and HPFRCC materials under monotonic and reversed cyclic loading conditions.分析研究的主要目的是根据实验中观察到的主要机制以及从获得的测试结果中制定粘合压力与滑动模型，以增强条形和预应力链。根据调查结果，将提出建议，以修改ACI代码中给出的有关加固条和预应力链和预应力链中给出的传输长度方程，如果需要，将提出新的方程式，如果需要，全球建筑行业面临着高级材料的需求，对高级材料的需求不断增长，以应对更加严格的范围，需要更加严格的范围，需要更长时间的服务，需要更长时间的维修寿命，需要修复效果，并需要维修效果，并需要维修效果，并降低了维修费用。这项研究通过容易使用高性能纤维钢筋混凝土来满足上述需求；这将允许开发新的结构概念，并提供改善现有设计性能的手段。在教育领域，将重点放在吸引本科生，尤其是与女工程师协会和密歇根大学少数民族工程计划办公室合作，以吸引本科生。将开发致力于这项研究的网站，并将包含与实验和分析研究以及课程材料有关的相关信息。总体而言，这项研究将增加知识库，并将使学生在结构应用中使用高级材料。