NEESR: Near Collapse Performance of Existing Reinforced Concrete Frame Buildings

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Column shear-axial failure in existing vulnerable reinforced concrete (RC) frame buildings constructed before the mid 1970's is a major seismic risk. The challenges associated with spatial response and system load redistribution capability at the onset of collapse has not been resolved yet. The acceptance criteria in current seismic rehabilitation provisions are defined at the element level with no due consideration for the system robustness. Four sets of three-dimensional, geographically distributed hybrid simulations (HS) will be conducted using the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) facility at the University of Illinois at Urbana-Champaign to obtain the response up to collapse of a representative three-dimensional structural system subjected to one-directional and tri-axial seismic ground motions. This research will investigate, characterize, model, and derive practical procedures for the consequences of column shear-axial failure on the collapse of existing vulnerable RC structures. The project will develop system-level acceptance criteria and analytical tools for near collapse seismic performance of existing non-ductile RC frame structures. Data from this project will be archived and made available to the public through the NEES Project Warehouse/data repository at http://www.nees.org. This project is a collaborative effort between researchers from Northeastern University and Western Michigan University.This project utilizes the unique HS capability provided by the NEES facility to simulate near collapse response of existing vulnerable RC buildings through the integration of large scale physical experiments and numerical models. If successful, this research project will shift the philosophy of structural assessment of vulnerable buildings from component-level to system-level evaluation. The application of system-level evaluation methods developed in this project can lead to more efficient and cost-effective rehabilitation methods for existing non-ductile RC buildings against collapse by identifying and prioritizing buildings susceptible to partial/total collapse. Thus, optimal use of limited resources can be made. A multi-level education and outreach program will provide students from K-12, college, and underrepresented groups, as well as high school physics teachers, with the opportunity to participate in project activities. This will include development of three teaching modules suitable for elementary, middle, and high school students covering the basics of earthquake engineering and topics relevant to collapse analysis. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).