Uncertainties in the seismic hazard parameters such the epicentral distance and intensity of future earthquake events as well as in the stochastic models used to describe the corresponding ground motion time-histories have significant impact on the calculated seismic risk for structural systems. The objective of this research is to develop a computationally efficient new framework to quantify the importance of such risk factors on the structural system performance and the design ground motion selection. To accomplish this goal, a probabilistic simulation-based methodology will be formulated to calculate the seismic risk for structural systems. Numerically efficient approaches based on stochastic sampling and recent advances in computer and computational science will be developed for sensitivity analysis to quantify the influence of the uncertain model characteristics on seismic risk. These approaches will be applied to a variety of structural systems with diverse performance definitions. The project will provide a methodology for efficient probabilistic sensitivity analysis and for quantifying the importance of various risk factors in the seismic structural design practice.
The research will significantly advance our understanding of the impact of various seismic-risk factors and is expected to influence the future earthquake risk mitigation strategies. This research effort will educate the future generation of researchers and professionals about the potentials of simulation-based engineering science for handling uncertainties. This study will be used as a resource to improve the undergraduate curriculum by offering a new elective course in seismic design. The project will provide advanced training to graduate students and every effort will be made to recruit these students from the underrepresented groups by leveraging the success of existing programs at Notre Dame. Undergraduate researchers will also be involved in the project to develop web-based tools for wide and effective dissemination of the work.
This project developed an analytical framework and computational tools to advance our understanding of the seismic hazard when stochastic ground motion models are adopted for the description of this hazard. This understanding can provide invaluable insight and guidance in design ground motion selection, with ultimate goal to improve seismic risk mitigation approaches and enhance resilience of our communities against earthquake hazards. In parallel, the project provided a platform for the education of future generation of researchers and professionals about the potential of simulation-based engineering science for statistical analysis and risk estimation. In particular, new numerical tools employing advanced stochastic simulation concepts were developed to efficiently identify the importance of the different risk factors in seismic risk assessment applications. This identification ultimately disaggregates the total risk to its contributing components, providing tremendous insight in better understanding risk. In parallel, a framework was established for quantification and assessment of risk using a simulation-based foundation and stochastic ground motion modeling, demonstrating the tremendous potential of this approach over other popular alternatives for quantification of seismic hazard. This demonstration leveraged primarily advances in computer and computational science (faster and more powerful computers) that have recently reduced the computational burden associated with simulation-based approaches A range of benchmark applications were then examined, considering different risk scenarios and the behavior of a range of different infrastructure systems, including bridges or applications of enhanced seismic mitigation measures such as isolation techniques. Through these studies the great potential of the proposed modeling tools was validated; parallel/distributed computing along with advanced stochastic simulation techniques can support a versatile seismic risk assessment when stochastic ground motion models are utilized, whereas sensitivity analysis can be seamlessly integrated in the approach to provide invaluable insight about the different risk factors contributing to the risk. This information can be ultimately utilized to better understand the vulnerabilities of our structural system when considering mitigative strategies but also guide future research in the field of seismic hazard characterizations. The latter is facilitated by providing a deeper understanding about what characteristics of our established models are the ones that seismic risk is more sensitive to (these are the ones we need to focus on in future developments). Vulnerabilities of existing models were identified and guidelines for future research development were developed, including guidelines for enhancement of the models for description of the seismic hazard in regions close to active faults (impacted by the so-called near-fault excitations). To support the broader impacts of the project, automated standalone tools were developed and disseminated through the project web-page. These tools allow other researchers to directly integrate key components of this research into their own work. With respect to educational developments, four graduate students and two undergraduate students (one completed an Honor’s thesis based on his participation on this project) have participated in this project, which has offered a unique opportunity of training in advanced statistical methodologies, structural simulation in parallel computational environments, and probabilistic risk assessment. This training provided them with an extra advantage over others trained in conventional structural engineering settings. Both undergraduate students continued to pursue graduate studies. The research developments were also integrated in two of the elective classes the PI offers at the University of Notre Dame, utilizing a ptoject-based learning modules, and were showcased in his participation in the 2013 National Academy of Engineering Frontiers of Engineering Education Symposium. In the context of this project a presentation was also given in the Early Childhood Development Center (at Notre Dame) kindergarten class, utilizing a portable shake table system to demonstrate the impact of earthquakes on structures, to promote the civil engineering discipline and the importance of seismic hazard mitigation.
