Natural hazards are a growing risk across the globe. As regions have urbanized, single events impact greater proportions of the population, and the populations within those regions have become more dependent on infrastructure systems. Regional resilience has become closely tied to the performance of infrastructure. For a comprehensive risk assessment losses caused by lifeline outage must be considered alongside structural and nonstructural risks. Many well developed techniques quantify structural and nonstructural risk; however, there are insufficient procedures to determine the likelihood of lifeline outages. Including lifelines in seismic assessments will provide a comprehensive risk, improving a decision maker’s capacity to efficiently balance mitigation against the full spectrum of risks. An ideal lifeline risk assessment is infeasible due to the large geographic scale of lifeline systems and their system structure; these same characteristics also make them vulnerable to disruption in hazard events. Probabilistic methods provide solutions for their analysis, but many of the necessary analysis variables remain unknown. Continued research and increased collection of infrastructure data may improve the ability of advanced probabilistic methods to study and forecast performance of lifelines, but many inputs for a complete probabilistic model are likely to remain unknown. This thesis recognizes these barriers to assessment and proposes a methodology that uses consequences to simplify analysis of lifeline systems. Risk is often defined as the product of probability of failure and consequence. Many assessments study the probability of failure and then consider the consequence. This thesis proposes the opposite, studying consequence first. In a theoretical model where all information is available the difference in approach is irrelevant; the results are the same regardless of order. In the real world however, studying consequence first provides an opportunity to simplify the system assessment. The proposed methodology starts with stakeholders defining consequences that constitute ruin, and then the lifeline system is examined and simplified to components that can produce such consequences. Previously large and expansive systems can be greatly simplified and made more approachable systems to study. The simplified methodology does not result in a comprehensive risk assessment, rather it provides an abbreviated risk profile of catastrophic risk; risk that constitutes ruin. By providing an assessment of only catastrophic lifeline risk, the risk of greatest importance is measured, while smaller recoverable risk remains unknown. This methodology aligns itself with the principle of resilience, the ability to withstand shocks and rebound. Assessments can be used directly to consider mitigation options that directly address stakeholder resilience. Many of the same probabilistic issues remain, but by simplifying the process, abbreviated lifelines assessments are more feasible providing stakeholders with information to make decisions in an environment that currently is largely unknown.

This thesis presents the results of an investigation of a multiple degree of freedom (MDOF) structure with hyperelastic bracing using nonlinear and incremental dynamic analysis. New analytical software is implemented in the investigation of the structure, and the study seeks to investigate the effectiveness of hyperelastic bracing as a seismic protection device. Hyperelastic braces incorporate a new idea of a nonlinear elastic material that gains stiffness as the brace deforms. Structural behaviors of particular concern for an MDOF frame are stability, residual displacement, base shear, and dispersion. The structure is analyzed under two ground motion records of varying content, and for two separate P-Delta cases of varying severity. Two sets of hyperelastic braces are investigated for their influence under the two ground motions and two P-Delta cases. Each scenario is analyzed using nonlinear dynamic analyses to investigate the response histories, and Incremental Dynamic Analysis (IDA) to investigate dispersion and the behavior of specific response measures as ground motion intensity increases. IDA curves are created for interstory drift and base shear for comparison between the two response measures. The research shows that the inclusion of hyperelastic braces in the MDOF frame improves the overall stability of the structure and reduces the amount of dispersion and residual displacement. The hyperelastic braces are shown to give positive performance characteristics while not detrimentally increasing system forces under regular service loads. The results highlight the benefit of the unique stiffening properties of hyperelastic braces as a seismic protection device. / Master of Science

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Earthen levees are crucial components of a nation's flood protection system. However, in some regions, these levees face the unique challenge of being subjected to both floods and earthquakes throughout their lifespan, an aspect that is relatively unexplored in the existing literature. The primary aim of this research is to examine earthquakes' and floods' effects on earthen levee failures. Using numerical simulations, the seepage, slope stability, and liquefaction potential of an earthen levee were modeled by considering compound of different floods and earthquakes scenarios. Elkhorn Levee in Sacramento, CA, was used as a representative case study for the simulations. The probability of levee failure and the extent of the breach caused by compound flood-earthquake scenarios are further determined by Fault Tree Method. The findings provide a practical approach to analyzing levee systems under multi-hazard conditions and enhancing levee resilience.

The purpose of this project is to simulate the detection of γ-ray spectra emitted by radon isotopes and their daughters. This is done as a contribution to the development of radiation detectors to be used in a research project investigating the possibility of using increased amounts of the radioactive gas radon as an earthquake precursor. Before the onset of an earthquake, microcracks are formed in the surrounding stone structures due to stress, releasing greater than usual amounts of radon gas contained within the rock pores. A way of predicting an upcoming earthquake would then be to place radiation detectors in areas with high seismicity in order to measure possible changes. This could be done in soil, groundwater (via springs, wells, and boreholes), or air. In this project, we aim to understand how measurements in groundwater would differ from ones in air, and how to best make use of the spectra as seen in water. This was done by simulating a scenario in which a scintillator detector, made of cesium iodide, is placed in each media and then assessing the resulting γ-ray spectra.

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