EAGER: Informing Infrastructure Decisions through Large-Amplitude Forced Vibration Testing

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The societal problems presented by aging civil infrastructures in the US are pervasive - cutting across diverse structures associated with our flood protection systems, existing building stock, and transportation networks. In recognition of the life safety risks posed by such systems under natural and anthropogenic hazards, there has been significant attention paid to the development of reliable safety assessment approaches to support their management, adaption, and reuse. What began with a near-exclusive reliance on visual inspections and simplified simulation models has evolved over the last several decades to embrace the impressive array of sensing technologies, highly refined simulation models, and model calibration techniques now available. Although these advances are significant, there remains no approach capable of assessing the safety of both the structure and the foundation system in a reliable manner. The aim of this EArly-concept Grant for Exploratory Research (EAGER) project is to overcome this barrier through the use of large amplitude shakers that were originally envisioned for evaluating soil properties. If this re-purposing of these large shakers proves successful, this research will remove a critical barrier to our ability to forecast the service life of existing infrastructure systems and, in turn, to make sound decisions about their adaption and reuse. In addition to this technical contribution, this research will expose and attract high schools students to engineering (through the development and implementation of a competition based outreach effort) and will recruit graduate students (who will be supported through project funds) from traditionally underrepresented groups through a host of on-going programs at Rutgers University. The project aims overcoming limitations of existing dynamic testing methodologies for structural systems. While cost-effective methodologies exist, they suffer from a reliance on low-amplitude, uni-directional excitation, which is unable to overcome intermittent stick-slip mechanisms or to induce appreciable responses within the substructure-foundation system. Therefore, to overcome these low-level mechanisms in a controlled manner, and improve the reliability of the resulting safety assessment, the research team will use large-amplitude mobile shakers that are available through the NSF NHERI Program. Although originally envisioned for geotechnical engineering seismic-related research, such shakers open opportunities for pushing the structural-foundation system beyond their low-level responses to reveal performance characteristics that are more representative of the expected behavior under safety limit states. By overcoming the mechanisms that exist only at low-levels, a more realistic distribution of forces will be captured, which will greatly enhance the reliability of simulation model predictions associated with the onset (both load levels and spatial location) of material nonlinearity. To meet this overarching goal, the following more focused objectives will be pursued:(1) Develop, evaluate, and refine a series of forced vibration testing and control strategies to capture response measurements indicative of key performance attributes of substructure/foundation and superstructure systems.(2) Develop, evaluate, and refine a series of both model-free and model-based data interpretation frameworks for structural system (foundation-substructure-superstructure) identification and assessment.(3) Perform a validation of the testing/control strategies and data interpretation frameworks on an operating structure with known substructure, foundation, and soil characteristics