Community resilience has been addressed across multiple disciplines including environmental sciences, engineering, sociology, psychology, and economics. Interest in community resilience gained momentum following several key natural and human-caused hazards in the United States and worldwide. To date, a comprehensive community resilience model that encompasses the performance of all the physical and socio-economic components from immediate impact through the recovery phase of a natural disaster has not been available. This paper summarizes a literature review of previous community resilience studies with a focus on natural hazards, which includes primarily models of individual infrastructure systems, their interdependencies, and community economic and social systems. A series of national and international initiatives aimed at community resilience are also summarized in this study. This paper suggests extensions of existing modeling methodologies aimed at developing an improved, integrated understanding of resilience that can be used by policy-makers in preparation for future events.

Building damage after an earthquake, or other hazard event, can interrupt businesses, displace households, and significantly disrupt a community for years. As a result, policymakers and engineers are working toward new design guidelines and policies that reduce the vulnerability of the built environment through improved building functional recovery performance. This study proposes a method for assessing post-earthquake building performance states of function and reoccupancy within the architecture of performance-based earthquake engineering, targeted at US construction, making use of Federal Emergency Management Agency (FEMA) P-58 fragility and consequence models. This is accomplished by mapping component damage states to systems-level operational performance, and then to building-level performance states, through a series of fault trees. The study also proposes a repair scheduling algorithm to estimate the time taken to restore building reoccupancy or function, considering impeding factors that delay the start of repairs. The result is a probabilistic approach that extends the performance-based engineering framework to explicitly quantify post-earthquake building function performance states, thus facilitating design and mitigation decisions for recovery-based performance objectives.

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High-voltage bushings have exhibited vulnerability during past earthquakes. The good performance of bushings mounted on a rigid base observed during shake table testing does not correlate well with their performance in the field. It is suspected that the seismic performance of high-voltage bushings is improved when mounted on a rigid base, as opposed to when mounted on more flexible cover plates of transformers. In this first of two companion papers, the seismic response of bushings was investigated numerically for various mounting conditions. The addition of flexural stiffeners on the transformer cover plates was explored as a means to stiffen the base of the bushings and mitigate their seismic vulnerability. Linear dynamic analyses conducted on four transformer-bushing system models showed that the simple approach of stiffening the cover plates of transformers is beneficial to the seismic response of high-voltage bushings.

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A numerical study conducted on four transformer-bushing models presented in a first companion paper indicated that high-voltage bushings mounted on the cover plates of transformers are more vulnerable to seismic loading than bushings mounted on a rigid base. This would explain why the good performance of bushings mounted on a rigid base observed during shake table testing does not correlate well with their performance in the field. In this second companion paper, the addition of flexural stiffeners on the transformer cover plates as a means to stiffen the base of bushings and mitigate their seismic vulnerability is investigated experimentally. Shake table testing was conducted on a 230 kV porcelain bushing mounted on a support structure incorporating a flexible cover plate and two stiffener configurations. Test results confirmed that stiffening the cover plates is beneficial to the seismic response of high-voltage bushings. Test results are compared to the predictions of finite element analyses.

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