NEESR-CR: Full-Scale RC and HPFRC Frame Subassemblages Subjected to Collapse-Consistent Loading Protocols for Enhanced Collapse Simulation and Internal Damage Characterization

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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 University of Texas at Arlington (lead institution), California State University at Chico (subaward), University of Illinois at Urbana-Champaign (subaward), and the University of Minnesota (subaward). The project will utilize the NEES equipment site at the University of Minnesota, the Multi-Axial Subassemblage Testing (MAST) Laboratory. Reinforced concrete (RC) structures comprise a large number of the buildings and bridges around the world. The collapse resistance of RC structures is not well understood, even though the collapse resistance is fundamental to the life-safety of building occupants during earthquakes. One of the primary problems is that currently available experimental test data are insufficient to allow researchers to comprehensively understand the collapse behavior of a building and develop accurate computer simulation models to predict when a building would collapse in an earthquake. The objective of this research is to advance knowledge about the collapse behavior and safety of both modern RC frame buildings and high performance fiber reinforced concrete (HPFRC) frame buildings when subjected to extreme earthquakes. This research project involves testing a comprehensive set of full-scale RC components and subassemblages all the way to collapse (nearly all currently available test data stop short of collapse); this comprehensive set of tests has been specifically planned for the purpose of better understanding collapse behavior and creating improved computer simulation models to predict the collapse safety of RC buildings. To improve understanding of how internal damage develops at small scales within the materials, advanced imaging technology (ultrasonic tomography) will be utilized during testing to characterize the progression of internal damage. To improve understanding of the collapse behavior of full large-scale RC buildings, improved computer simulation models will be developed and the collapse of RC building models will be directly simulated. Intellectual Merit: The following technical contributions are anticipated: (1) new calibrated RC/HPFRC component models, (2) new understanding of collapse resistance behavior of RC frame buildings constructed with RC and HPFRC materials; (3) development of internal imaging technology that could be used as an on-site structural assessment tool; and (4) understanding of the internal damage development and mechanisms for RC columns and slab-beam-column connections subjected to cyclic loading. Broader Impacts: Results from this study will provide comprehensive information for collapse assessment of newly constructed RC moment frames, as well as moment frames constructed from an emerging high performance material (HPFRC). Such information will be necessary to support widespread use of HPFRC. The development of advanced imaging technology for concrete structures will provide new diagnostic capability to ascertain structural damage within concrete members, for example immediately after an earthquake event. The collapse simulation and imaging techniques developed in this research will be incorporated into educational tools to introduce undergraduate students to earthquake engineering research, the significance of earthquake effects, and the behavior of building structures subjected to collapse-level ground motions. Additionally, undergraduate students at the California State University at Chico will directly participate in the research. The interdisciplinary work plan will promote the development of professionally prepared graduate students who have exposure to a broad range of cross-cutting technologies. 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).