NEESR-CR - Innovative Seismic Retrofits for Resilient Reinforced Concrete Buildings

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This award is an outcome of the NSF 09-524 program solicitation "George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)" competition and includes the Georgia Institute of Technology (lead institution), Howard University (subaward), and Rice University (subaward). The project will utilize the NEES mobile shakers operated by the University of California, Los Angeles.The project team will evaluate the efficacy of a new class of innovative systems with recentering and/or high damping capabilities, and develop a framework for their design and implementation to retrofit reinforced concrete (RC) buildings to improve seismic performance. The goal is to validate, via innovative large scale field testing, a new class of retrofits for RC buildings. Five retrofit measures will be investigated, consisting of novel bracing systems, beam-column connection elements, or columns wraps. Common advantageous characteristics of the systems include the ease of application (requiring little-to-no heavy machinery), scalability and adaptability, passive nature, and need for little-to-no maintenance through the life-cycle. Furthermore, these systems aim to provide improved seismic performance in terms of minimal damage, enhanced post-event functionality, and improved cost-benefit compared to traditional retrofit approaches. The use of advanced materials in innovative systems will result in improved seismic retrofits for RC buildings that may find more widespread adoption due to their efficient design, minimal maintenance or disruption for installation, and enhanced cost-effectiveness. The research includes a series of unique multi-scale experiments, coupled with detailed finite element simulations, fragility analyses, and cost-benefit studies. Research, education, and outreach plans include the following key components: (1) first of its kind full-scale system-level validation of innovative retrofit systems (many based on shape memory alloys) using the NEES mobile shakers; (2) code-based designs of retrofit measures, in collaboration with experienced design professionals; (3) damage detection approaches using wireless sensors that project detailed information on the condition of the innovative retrofits, and the system response; (4) detailed fragility analyses, or vulnerability models, of buildings with and without retrofit; (5) cost-benefit and life-cycle cost analyses to inform decision-makers on optimal building retrofits; (6) international cooperation on reduced-scale system-level tests with Sherbrooke University in Canada, and medium-scale testing at National Taiwan University, and Hongik University (Korea); (7) a comprehensive outreach and education program impacting all levels (K-12, college, and industry); and (8) workshops focused on technology transfer with industry leaders.Intellectual Merit: This research provides the first large-scale validation of high performance systems based on a series of multi-scale component and full-scale system-level field tests. Detailed analytical modeling and fragility analyses will be performed to assess the impact of various innovative retrofits on reducing the seismic vulnerability of RC buildings. A framework will be established, ranging from smart sensing and structural damage state estimation, to fragility modeling, performance assessment, and cost-benefit studies of retrofitted RC buildings. The validation of the new systems are expected to provide a marked advance in performance (seismic and life-cycle) through innovative design, material usage, and implementation to transform current approaches for seismic retrofit of buildings.Broader Impacts: The broader impacts of the proposed research, education, and outreach program are four-fold. First, the novel multi-scale testing, coupled with detailed analysis, will provide the first known system-level validation of such high performance systems. Second, the efficiency, cost-effectiveness, and minimal disruption caused by retrofits proposed can result in superior retrofit approaches with broad application to improve building performance nationwide. Third, the collaboration with industry partners and field testing of retrofits in real structures will address realistic challenges of implementation and streamline transfer to practice. A series of workshops will bring together academics, researchers, and industry to advance the transfer of innovative systems for seismic building retrofit. Fourth, a multi-faceted education program addresses the need to improve high school science and engineering curriculum, while addressing the lack of underrepresented students pursuing degrees in the STEM (science, technology, engineering, and mathematics) arena.Data from this project will be archived and made available to the public through the NEES data repository. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).