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

开发预制楼盖的抗震设计方法-CMS 0324522PI：Robert Fleischmann，Arizona由亚利桑那大学(UA)、加州大学圣地亚哥分校(UCSD)和利哈伊大学(LU)组成的财团，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，旨在为地震荷载下建筑物的预制混凝土楼盖开发一种全面、准确和高效的设计方法。在这一合作中，大学提供了地震荷载下预制楼板横隔板的关键问题的知识，以及所需的分析和实验专业知识和设施。代表全国预制混凝土行业的PCI带来了行业实践、标准和经济方面的知识，以及项目联合融资。利用紧密结合的实验和分析模拟，该项目将显著提高对预制楼板隔板抗震性能的了解，并发展关于关键预制隔板构件的刚度、强度和延性能力的信息。将这些结果与行业知识相结合，该项目将产生一种适当的抗震设计方法。该项目是作为产学合作项目向国家自然科学基金会学术联系机会(GOALI)项目提出的。预制混凝土楼板横隔板抗震设计方法的发展具有挑战性，并解决了几个关键问题：(1)横隔板中产生的地震力水平取决于横隔板和主要抗侧向力构件(如剪力墙和抗弯框架)之间的动力相互作用；(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性能；(3)由于第(1)项和第(2)项，很难对横隔板设计力进行简单、准确的估计；(4)预制横隔板的非弹性行为，包括内力抵抗机制，以及关键构件的变形要求和能力，由于这些横隔板的连接性质，是复杂的和难以理解的；(5)需要将横隔板锚固到横向抗力单元上的细节；(6)由于预制楼板横隔板的灵活性，需要准确地估计对建筑物抗重力系统的横向漂移需求。为了解决这些问题，该联盟的研究将结合以下内容：(1)通过应用简单的循环受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横隔膜元件的灵活性、强度和延性；(2)对完整的楼板横隔膜(在地震荷载下)进行详细的有限元(FE)分析，以确定将在试验中应用并用于制定横隔膜设计要求的横隔膜元件的临界力模式和历史；(3)原型建筑的非线性时程动力分析(NTDA)，以确定横隔板地震力水平；(4)整个结构的准静态横隔板试验和振动台试验，以验证有限元和NTDA的结果，并为关键横隔板构件的大型试验提供补充；以及(5)预制施工方法和经济性、设计实践和设计规范制定问题的行业知识。智力上的功绩。该项目将对楼板横隔板与主要抗侧力构件之间的动力相互作用有新的认识，在横隔板柔度不可忽略且可能出现非弹性行为的情况下。该项目还将发展关于预制横隔板的非弹性行为的新知识，由于预制系统的接缝性质以及跨接缝的钢筋的灵活性和有限的变形能力，预制横隔板的非弹性行为是复杂的。为了实现这些目标，该项目将推进最先进的大规模实验模拟与分析模拟的集成，这种集成将跨机构完成，由UA提供分析模拟，以推动LU和UCSD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对该项目的财政捐款(42.6万美元)证明了业界的兴趣。项目成果在部署后，将产生安全和经济的预制横隔板设计。此外，该项目将支持4名研究生，他们将从研究和与行业从业者的互动中获得教育。研究成果将用于参与的大学的研究生课程和行业从业者的短期课程。

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.