NEESR-SG: Seismic Performance Assessment and Retrofit of Non-Ductile RC Frames with Infill Walls

填充物中的无筋砖砌体常被用作建筑物的内部隔断和外墙，通常被视为非结构构件。然而，与大多数非结构构件不同的是，在地震荷载作用下，它们可以与约束框架产生强烈的相互作用，因此对结构的横向刚度和抗力有很大贡献。尽管这些研究跨越了几十年，但这些结构在严重地震中的性能仍然是当今结构工程师和研究人员之间的一大争议。这项研究的主要目的是开发合理可靠的方法来评估无填充钢筋混凝土框架的抗震安全性和性能，并开发实用而有效的技术来使用传统材料和创新材料对这些结构进行抗震加固。该项目将包括开发可靠的分析工具，范围从先进的计算模型到可用于工程实践的简单分析方法。该项目将利用NEES提供的大量计算资源和实验设施。分析方法和改装技术将首先通过与科罗拉多大学博尔德分校的NEES快速混合测试设施进行的中型实验进行验证。最终的概念验证测试将在一个3/4比例的三层RC框架上进行，使用的是加州大学圣地亚哥分校的NEES大型高性能室外振动台。斯坦福大学将专注于开发可喷涂的高性能纤维增强水泥基复合材料，用于填充改造。这项工作将由一个在专业实践、结构设计、结构测试、结构分析、计算力学和复合材料方面具有专业知识的不同研究团队进行，作为一项多机构、跨学科的努力。了解和评估填充砌体的非延性钢筋混凝土框架的抗震性能是结构工程中最难解决的问题。目前，对于这一点还没有可靠的工程指南。评估复杂的框架-填充物相互作用和由此产生的破坏机制的分析工具需要建立在力学的基本原理和合理的工程判断的基础上。这比分析纯RC或砖石结构要具有更大的挑战性。这项研究将填补这类现有结构的建模和性能评估方面的一个主要空白，这些结构经常出现在地震高危地区，并制定有效的改造策略，从系统的角度防止不希望看到的破坏机制。该项目将涉及开发新的设计和评估技术、新材料和尖端计算方法，这将是智力上的激发。加州大学圣地亚哥分校、加州大学伯克利分校和斯坦福大学已经实施的成功的教育和外展计划所提供的杠杆作用，以及将在NEES之外获得的额外资源，将加强NEESincc的共同教育和外展目标。利用协作工具进行的拟议循环法研究和外联活动，以及NEES网格提供的远程呈现和数据存档和挖掘能力，将确保及时向广大工程界和非工程界传播信息。该项目开发的先进计算模型将很容易应用于许多新的和现有的结构，并提供基于3-D模型的模拟能力，在可预见的未来可能取代物理实验。在NEES网格支持的公共领域软件OpenSEES中实施先进的计算模型，将使整个地震工程界受益。所探索的翻新技术可能会为建筑物业主带来巨大的节省，并提高大量现有结构的抗震安全性。简化的分析工具、设计和评估方法以及试验数据将为下一代基于性能的此类结构抗震设计指南提供急需的信息和工具。该项目的设计、计算和试验一体化，为未来地震工程师进行基于性能的工程培训提供了独特的经验。

ABSTRACTUnreinforced masonry in fills are frequently found as interior partitions and exterior walls in buildings, and are normally treated as non-structural elements. However, unlike most non-structural components, they can develop a strong interaction with the bounding frames when subject to earthquake loads and, therefore, contribute significantly to the lateral stiffness and load resistance of the structure. In spite of the research that have spanned several decades, the performance of these structures in a severe earthquake remains a major controversy among structural engineers and researchers today. The main aim of the proposed research is to develop rational and reliable methodologies for assessing the seismic safety and performance of masonry unfilled RC frames, and develop practical and effective techniques for the seismic retrofit of these structures using conventional as well as innovative materials. The project will include the development of reliable analysis tools that range from advanced computational models to simple analytical methods that can be used in engineering practice. The project will take advantage of the vast computational resources and experimental facilities provided by NEES. The analysis methods and retrofit techniques will be first validated with medium-scale experiments to beconducted with the NEES Fast Hybrid Test facility at the University of Colorado at Boulder. Final proof-of-concept tests will be conducted on a 3/4-scale three-story RC frame using the NEES Large High Performance Outdoor Shake Table at the University of California at San Diego. Stanford University will focus on the development of sprayable high-performance fiber-reinforced cement-based composites for infill retrofit. The work will be carried out as a multi-institutional, inter-disciplinary effort by a diverse research team with expertise in professional practice, structural design, structural testing, structural analysis, computational mechanics, and composite materials. Understanding and assessing the seismic performance of masonry-infilled non-ductile RC frames presents a most difficult problem in structural engineering. Currently, there are no reliable engineering guidelines for this. Analytical tools to evaluate the complicated frame-infill interaction and the resulting failure mechanisms need to be built on the fundamental principles of mechanics and sound engineering judgment. It is far more challenging than analyzing a pure RC or masonry structure. This research will fill a major gap in the modeling and performance assessment of this class of existing structures that can be frequently found in regions of high seismic risk and the development of effective retrofit strategies to prohibit the undesired failure mechanisms from a system perspective. The project will involve the development of new design and assessment techniques, new materials, and cutting-edge computational methods, which will be intellectually stimulating. The leverage provided by the successful programs on education and outreach that are already in place at UCSD, CU, and Stanford, and the additional resources that will be secured outside NEES will reinforce the common education and outreach goals of NEESinc. The proposed round-robin studies and outreach activities using the collaboratory tools, and the telepresence and data archiving and mining capabilities provided by the NEESgrid will assure timely dissemination of information to the broad engineering and lay communities. The advanced computational models developed in this project will be readily applicable to many new and existing structures and provide a 3-D model-based simulation capability that can potentially replace physical experiments in a foreseeable future. The implementation of the advanced computational models in a public-domain software, OpenSEES, which is supported by the NEESgrid, will benefit the earthquake engineering community at large. The retrofit techniques explored can potentially lead to significant savings by building owners and enhance the seismic safety of a large number of existing structures. The simplified analytical tools, design and assessment methodologies, andexperimental data will provide the much needed information and tools for the next-generationperformance-based seismic design guidelines on this class of structures. The integration of design, computation, and experimentation in this project provide a unique experience for the training of future earthquake engineers on performance-based engineering.