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1. Informally-Constructed houses in Puerto Rico under Earthquake load:Building Capacity for Safer Post-disaster Shelter: Leveraging Local Understanding and Advanced Engineering Assessments

   https://doi.org/10.17603/ds2-gyhe-jk11  

   Murray, Polly; Feliciano, Dirsa; Goldwyn, Briar; Liel, Abbie; Arroyo, Orlando; Javernick-Will, Amy (January 2024, Designsafe-CI)

   More than 1.6 billion people worldwide live in informally constructed houses, many of which are reinforced with concrete. Patterns of past earthquake damage suggest that these homes have significant seismic vulnerabilities, endangering their occupants. The characteristics of these houses vary widely with local building practices. In addition, these vulnerabilities are potentially exacerbated by incremental construction practices and building practices that address wind/flood risk in multi-hazard environments. Yet, despite the ubiquity of this type of construction, there have not been efforts to systematically assess the seismic risks to support risk-reducing design and construction strategies. In this study, we developed a method to assess the seismic collapse capacity of informally constructed housing that accounts for local building practices and materials, quantifying the effect of building characteristics on collapse risk. We exercise the method to assess seismic performance of housing in the US. Caribbean Island of Puerto Rico, which has high seismic hazard and experiences frequent hurricanes. This analysis showed that heavy construction, often due to the addition of a second story, and the presence of an open ground story leads to a high collapse risk. Severely corroded steel bars could also worsen performance. Although houses with infill performed better than those with an open ground story, confined masonry construction techniques produced a major reduction in collapse risk when compared to infilled or open-frame construction. Infill construction with partial height walls performed very poorly. Well-built reinforced concrete column jackets and the addition of infill in open first-story bays can reduce the greater risks of openground- story houses. These findings, which are quantified in the results portion of this article, are intended to support the development of design and construction recommendations for safer housing.There is an urgent need to improve community capacity to recover more effectively after disasters through safer design and construction practices. To do this, training programs need to foster an improved understanding of shelter design and construction to withstand future wind and earthquake events. This project analyzed informal builders’ perceptions of housing safety in Puerto Rico (responding to 2017's Hurricane Maria and the 2019-2020 earthquake swarm) and homeowner’s perceptions of housing safety in Philippines (responding to 2013's Typhoon Haiyan and 2017's Ormoc earthquake) to: (1) assess local understanding of shelter safety in multiple hazards, including causal factors influencing this understanding, through a household survey in the Philippines and a survey to informal contractors in Puerto Rico; (2) assess the expected performance of various post-disaster shelter typologies to quantify safety during future earthquake and wind events using performance-based engineering methods, developing a rapid screening tool that can be used in design or evaluation; (3) identify conflicts between perceived and assessed safety of shelter, and why these conflicts exist, by comparing engineering assessments with local perceptions; and (4) create a communication design for organizations assisting with training for safer housing construction. 

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2. Multi-Hazard Housing Safety Perceptions of Those Involved with Housing Construction in Puerto Rico

   https://doi.org/10.3390/su14073802  

   Goldwyn, Briar; Javernick-Will, Amy; Liel, Abbie B. (April 2022, Sustainability)

   Globally, hazards are increasingly threatening housing each year, and housing constructed outside the formal sector may be particularly vulnerable. Yet, limited studies have investigated the perceptions of those responsible for designing and building this housing. These safety perceptions motivate the informal housing construction practices that ultimately determine housing safety. Thus, this study investigates the multi-hazard housing safety perceptions of individuals involved with housing construction in Puerto Rico. We surveyed 345 builders and hardware store employees across Puerto Rico to understand their perceptions of expected housing damage in hurricanes and earthquakes, important mitigation measures, and barriers to safer housing construction. Our results reveal that prior hazard experience did not influence perceptions of expected housing damage, but previous housing construction experience did. Respondents viewed wood and concrete housing as less safe in hurricanes and earthquakes, respectively. Yet, respondents appeared uncertain about the importance of mitigation measures for concrete houses in earthquakes, likely due to a combination of limited earthquake experience and “hidden” reinforcement detailing in a reinforced concrete house. Interestingly, our results also show that respondents perceive technical construction capacity as a major barrier to safer informal housing construction rather than resource constraints alone. These findings suggest areas for technical construction capacity development for Puerto Rico’s informal construction sector. 

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3. Earthquake Resilience of Spatially Distributed Building Clusters: Methodology and Application

   https://doi.org/10.1061/JSENDH.STENG-12776  

   Esquivel, Silvestre Chan; Jia, Yiming; Sasani, Mehrdad (October 2024, Journal of Structural Engineering)

   Interest in earthquake resilience has increased in recent years, and the use of building cluster performance objectives has been shown to be an effective method for evaluating the resilience of built environment. A building cluster is a portfolio of buildings that share the same role in a community; its performance objectives are defined by considering earthquake scenarios, hazard levels, and individual building performance. The methodology presented in this paper employs performance-based assessments to estimate the probability of achieving building cluster performance objectives immediately following a seismic event. It can be used to assess the immediate post-earthquake community resilience in five steps: 1) hazard analysis, 2) conditional assessment of individual building performance, 3) conditional assessment of building cluster performance, 4) building cluster performance assessment by aggregation, and 5) earthquake resilience assessment of building clusters considering all hazard levels of interest. The design and extreme hazard levels are formulated using ground motion records selected based on the conditional spectra considering characteristics of earthquake scenarios and spatial correlation. Three performance objectives are defined for both individual buildings and building clusters: functionality, safe and usable during repair, and collapse prevention. Two engineering demand parameters – the maximum transient and the permanent interstory drift indices – are used to estimate individual building performance. The probability of achieving building cluster performance objective is calculated using the total probability theorem. The application of the proposed methodology is demonstrated using two clusters of reinforced concrete buildings, corresponding to ASCE 7 Risk Category II and IV structures, in San Francisco, CA. 

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4. Potential for mitigating hurricane wind impact on informally-constructed homes in Puerto Rico under current and future climate scenarios

   Valdivieso, Diego; Goldwyn, Briar; Liel, Abbie B; Javernick-Will, Amy; Lopez-Garcia, Diego; Guindos, Pablo (August 2024, International journal of disaster risk reduction)

   This study investigates the resilience of informally-constructed light-frame timber houses in Puerto Rico, a region where households with limited resources face significant risks from climate hazards, notably hurricanes. This study conducts a component-based, performance-based wind engineering assessment of informally-constructed house typologies, defined based on extensive fieldwork, under both existing and projected future climate conditions. Key findings highlight the effectiveness of certain mitigation strategies, such as reinforcing roof-to-wall connections, in significantly reducing the probability of failure. Fully-mitigated cases, which involve applying mitigation measures to the roof envelope, roof-to-wall connections, and shear walls, exhibited annual probabilities of failure that are much closer to, but do not necessarily meet, the threshold targeted by American building standards (i.e., ASCE 7). The results also show a dramatic increase in probability of failure of these houses projected by the adopted climate change model scenarios, driven by the increased frequency and intensity of hurricanes in Puerto Rico. Results from feedback from those working in the informal construction sector also identify challenges hindering the effective implementation of mitigation measures in Puerto Rican communities, including a lack of knowledge about how to implement the mitigation strategies and barriers related to real and perceived costs. Taken together these results underscore the urgent need for changes in building practices and revising building standards and suggesting potentially feasible mitigation strategies to improve those practices. 

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5. An integrated framework for seismic risk assessment of reinforced concrete buildings based on structural health monitoring

   Sheikh, I. A.; Khandel, O.; Soliman, M.; Haase, J. S.; & Jaiswal, P. (January 2019, International Association for Bridge and Structural Engineering Congress)

   null (Ed.)

   In recent years, several locations in the United States have been experiencing a significant increase in seismicity that has been attributed to oil and gas production. As oil and natural gas production in the United States continues to increase, it is expected that the seismic hazard in these locations will continue to experience a corresponding upsurge. However, many urban structures in these locations are not designed to withstand these increasing levels of seismicity. Accordingly, it is crucial to develop methodologies that can help us quantify the seismic performance of these structures, establish their risk levels, and identify optimal retrofit strategies that will enhance the seismic resilience of these structures. In this context, structural health monitoring (SHM) plays an important role in understanding the seismic performance of structures. SHM can be used, in conjunction with finite element modelling, to provide a realistic representation of the structural performance during a seismic event. In this paper, a framework for seismic risk assessment of reinforced concrete buildings based on SHM is presented. The framework combines nonlinear finite element modeling and SHM data to establish the seismic fragility profile of the structure. The approach is illustrated on a multi- story reinforced concrete structure located on the Oklahoma State University Campus. 

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