GOALI: Development of a Seismic Design Methodology for Precast Floor Diaphragms

预制楼板隔板抗震设计方法的发展——CMS 0324522PI由亚利桑那大学（UA）、加州大学圣地亚哥分校（UCSD）和里海大学（LU）组成的一个联盟，以及预制/预应力混凝土研究所（PCI）提出了一个合作研究项目，旨在为地震荷载下的建筑物预制混凝土楼板隔板开发一种全面、准确、高效的设计方法。在这次合作中，这两所大学带来了地震荷载下预制楼板隔板关键问题的知识，以及所需的分析和实验专业知识和设施。PCI代表全国预制混凝土行业，提供行业实践、标准和经济学知识，以及项目共同资助。通过紧密结合的实验和分析模拟，该项目将大大提高对预制楼板隔板抗震性能的认识，并开发有关关键预制隔膜元件的刚度、强度和延性能力的信息。将这些结果与行业知识相结合，该项目将产生合适的抗震设计方法。该项目已向美国国家科学基金会提出。作为产学研合作项目的学术联络资助机会（GOALI）计划。为预制混凝土楼板横膈膜开发适当的抗震设计方法具有挑战性，并解决了几个关键问题：(1)横膈膜中开发的地震力水平取决于横膈膜与主要抗侧力元件（例如剪力墙和抗矩框架）之间的动态相互作用；(2)动力相互作用取决于横隔板和横向力系统的弹性和非弹性行为；(3)由于第(1)和(2)项的原因，很难对隔板的设计力进行简单、准确的估计；(4)预制隔板的非弹性性能，包括内力抗力机制，以及关键元件的变形需求和能力，由于这些隔板的节理性质，是复杂的，而且很难理解；(5)需要将隔板锚定在抗侧力元件上的细节；(6)需要精确的方法来估计由于预制楼板隔板的柔性而对建筑物抗重力系统的侧向漂移需求。为了解决这些问题，该联盟的研究将整合以下内容：(1)通过应用简单的循环力模式和历史以及复杂的（多自由度）力模式和历史来确定关键膜片元件的柔韧性、强度和延性的大规模实验；(2)详细的有限元（FE）分析完整的地板隔板（在地震荷载下），以确定将在实验中应用的隔板元件的临界力模式和历史，并用于制定隔板设计要求；(3)原型建筑非线性时程动力分析（NTDA），确定隔震力水平；(4)整个结构的准静态膜片试验和振动台试验，验证有限元和NTDA结果，为关键膜片元件的大规模试验提供补充输入；(5)预制施工方法和经济，设计实践和设计规范开发问题的行业知识。知识价值。该项目将开发新的知识，在隔膜灵活性不可忽略和隔膜非弹性行为可能发生的情况下，地板隔膜和主要抗侧力元件之间的动态相互作用。该项目还将开发预制隔板的非弹性行为的新知识，这是复杂的，由于预制系统的节理性质和柔性和有限的变形能力，钢筋跨越节理。为了实现这些目标，该项目将在整合大规模实验模拟和分析模拟方面推进最先进的技术，这种整合将在跨机构完成，UA提供分析模拟，以推动洛杉矶大学和加州大学圣地亚哥分校的实验。更广泛的影响。该工程将直接影响预制混凝土建筑的抗震设计实践和规范。行业参与者和顾问的数量以及PCI对该项目的财务贡献（426,000美元）证明了行业的兴趣。该工程的应用结果将为安全、经济的预制隔膜设计提供依据。此外，该项目将支持4名研究生，他们将通过研究和与行业从业者的互动来接受教育。研究成果将用于参与大学的研究生课程和行业从业人员的短期课程。

Development of a Seismic Design Methodology for Precast Floor Diaphragms -- CMS 0324522PI: Robert Fleischmann, ArizonaA consortium comprised of the University of Arizona (UA), the University of California San Diego (UCSD), and Lehigh University (LU), together with the Precast/Prestressed Concrete Institute (PCI) proposes a collaborative research project to develop a comprehensive, accurate, and efficient design methodology for precast concrete floor diaphragms in buildings under seismic loading. To this collaboration, the universities bring knowledge of critical issues for precast floor diaphragms under seismic loads, as well as the required analytical and experimental expertise and facilities. PCI, which represents the precast concrete industry nationwide, brings knowledge of industry practices, standards, and economics, as well as project co-funding. Using closely integrated experimental and analytical simulations, the project will significantly advance knowledge of the seismic behavior of precast floor diaphragms and develop information on the stiffness, strength, and ductility capacity of critical precast diaphragm elements. Integrating these results with industry knowledge, the project will produce an appropriate seismic design methodology. The project is proposed to the NSF.s Grant Opportunities for Academic Liaison with Industry (GOALI) program as an Industry-University Collaborative Project. The development of an appropriate seismic design methodology for precast concrete floor diaphragms is challenging and addresses several critical issues: (1) the seismic force levels developed in diaphragms depend on dynamic interaction between the diaphragms and the primary lateral force-resisting elements (e.g., shear walls and moment resisting frames); (2) the dynamic interaction depends on the elastic and inelastic behavior of both the diaphragms and the lateral force systems; (3) as a result of items (1) and (2), simple, accurate estimates of design forces for diaphragms are difficult to make; (4) the inelastic behavior of precast diaphragms, including the internal force-resisting mechanisms, and the deformation demands and capacities of critical elements, is complex and poorly understood because of the jointed nature of these diaphragms; (5) details to anchor the diaphragms to the lateral force-resisting elements are needed; and (6) accurate methods to estimate the lateral drift demands on the building's gravity-force resisting systems due to the flexibility of precast floor diaphragms are needed. To address these issues, the consortium's research will integrate the following: (1) large-scale experiments to determine the flexibility, strength, and ductility of critical diaphragm elements by applying both simple cyclic force patterns and histories, and complex (multi-degree-of-freedom) force patterns and histories; (2) detailed finite element (FE) analyses of complete floor diaphragms (under seismic load) to determine critical force patterns and histories for diaphragm elements that will be applied in the experiments and used in developing diaphragm design requirements; (3) nonlinear time-history dynamic analyses (NTDA) of prototype buildings to determine diaphragm seismic force levels; (4) quasi-static diaphragm tests and shaking table tests of entire structures to verify the FE and NTDA results and provide added input into the large-scale experiments on critical diaphragm elements; and (5) industry knowledge of precast construction methods and economics, design practices, and design code development issues. Intellectual Merit. The project will develop new knowledge of the dynamic interactions between floor diaphragms and the primary lateral force-resisting elements under the conditions where the diaphragm flexibility is not negligible and inelastic behavior of the diaphragm is likely. The project will also develop new knowledge of the inelastic behavior of precast diaphragms, which is complex owing to the jointed nature of the precast system and the flexibility and limited deformation capacity of the reinforcement across the joints. To accomplish these goals, the project will advance the state-of-the-art in integrating large-scale experimental simulations with analytical simulations, and this integration will be accomplished across institutions, with UA providing the analytical simulations to drive experiments at LU and UCSD. Broader Impact. The project will directly impact seismic design practice and codes for precast concrete buildings. The interest of industry is evidenced by the number of industry participants and advisors, and PCI's financial contributions ($426,000) to the project. The project results, when deployed, will result in safe and economical precast diaphragm designs. In addition, the project will support 4 graduate students, who will be educated by the research and the interactions with industry practitioners. The research results will be utilized in graduate curriculum at the participating universities and in short courses for industry practitioners.