Collaborative Research: Time-Dependent Response of Reinforced Concrete Buildings near Collapse

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This research project will investigate the near-collapse behavior of reinforced concrete buildings under sustained gravity loads. Nearly half of the building collapses in the U.S. due to causes other than natural disasters are related to construction or design error, deterioration, or overloading. The majority of these failures result in partial or total collapse and occur during the service life of the building under sustained gravity loads. The formation of local damage and the evolution from local failure to global collapse are often not immediate; instead, they are complex time-dependent phenomena, for which little knowledge exists. The fundamental knowledge obtained from this project will facilitate better interpretation of early warning signs of building collapse for more prudent evacuation, rescue, and stabilization decisions; advance prediction and evaluation of a damaged building safety; and ultimately inform design for safer and more robust buildings able to resist collapse. These outcomes will reduce the economic and societal impact of building failure. The project will partner with the engineering community for immediate dissemination of the research, engage under-represented groups, and increase public scientific engagement, and positively impact engineering education.The impact of sustained loads on collapse evolution of two common types of reinforced concrete buildings, moment frames and flat-plates, will be studied by experimental simulations and numerical modeling. The project will identify and model the response of structural components sensitive to time-dependent concrete damage under sustained high stresses, examine and model the response of substructures under sustained high stresses caused by an initial local failure, identify system level response and the interaction among most impacted components, and evaluate collapse risk. At the material scale, the research generates knowledge for confinement effects on concrete creep at sustained high stresses; at the component scale, the research will generate knowledge of the effects of creep and shear crack opening on the sustained loading response of columns, axially restrained beams in frames, and slab-column connections; at the system scale, the research will lead to a crucial understanding the performance and collapse risk of frame and flat-plate systems under high sustained loads and the collapse evolution mechanism.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.