Porter K.,SPA Risk LLC |
Johnson G.,Halcrow |
Sheppard R.,Energo Engineering Inc. |
Earthquake Spectra | Year: 2010
A study for the Multidisciplinary Center for Earthquake Engineering Research (MCEER) provides fragility functions for 52 varieties of mechanical, electrical, and plumbing (MEP) equipment commonly found in commercial and industrial buildings. For the majority of equipment categories, the MCEER study provides multiple fragility functions, reflecting important effects of bracing, anchorage, interaction, etc. The fragility functions express the probability that the component would be rendered inoperative as a function of floor acceleration. That work did not include the evidence underlying the fragility functions. As part of the ATC-58 effort to bring second-generation performance-based earthquake engineering to professional practice, we have compiled the original MCEER specimen-level performance data into a publicly accessible database and validate many of the original fragility functions. In some cases, new fragility functions derived by ATC-58 methods show somewhat closer agreement with the raw data. Average-condition fragility functions are developed here; we will address in subsequent work the effect of potentially important - arguably crucial - performance-modifying factors such as poor anchorage and interaction. © 2010, Earthquake Engineering Research Institute.
Lizundia B.,Rutherford Chekene |
Durphy S.,Estructure |
Griffin M.,CCS Group Inc. |
Holmes W.,Rutherford Chekene |
And 4 more authors.
Improving the Seismic Performance of Existing Buildings and other Structures 2015 - Proceedings of the 2nd ATC and SEI Conference on Improving the Seismic Performance of Existing Buildings and Other Structures | Year: 2015
FEMA P-154 Rapid Visual Screening of Buildings for Potential Seismic Hazards: A Handbook and the companion publication FEMA P-155: Supporting Documentation provide a methodology for rapid visual screening of buildings for potential seismic hazards. The Handbook provides a "sidewalk survey" approach that enables classification of buildings into two categories: those that appear to be adequately safe and those that may be seismically hazardous and should be evaluated in more detail. The First Edition of the Handbook was published in 1988, and it was updated to the Second Edition in 2002. The methodology has been used extensively throughout the United States by private sector organizations and government agencies to screen buildings, and it has served as a model for similar efforts in other countries. In a project funded by FEMA, the Applied Technology Council updated both FEMA P-154 and FEMA P-155. Major enhancements in the Third Edition include improvements in the screening form; an added optional more detailed level of screening; updates of the scoring methodology; more refined seismicity regions; new reference guides for vertical and plan irregularities; additional building types; improved consideration of additions, adjacent structures, and retrofits; an optional electronic scoring methodology; new insight into risk; and more detailed discussion on how to run an effective screening program. © 2015 ASCE and ATC.
Porter K.,SPA Risk LLC |
Jones L.,U.S. Geological Survey |
Cox D.,U.S. Geological Survey |
Goltz J.,California Governors Office of Emergency Services |
And 11 more authors.
Earthquake Spectra | Year: 2011
In 2008, an earthquake-planning scenario document was released by the U.S. Geological Survey (USGS) and California Geological Survey that hypothesizes the occurrence and effects of a Mw7.8 earthquake on the southern San Andreas Fault. It was created by more than 300 scientists and engineers. Fault offsets reach 13 m and up to 8 m at lifeline crossings. Physics-based modeling was used to generate maps of shaking intensity, with peak ground velocities of 3 m/sec near the fault and exceeding 0.5 m/sec over 10,000 km2. A custom HAZUS®MH analysis and 18 special studies were performed to characterize the effects of the earthquake on the built environment. The scenario posits 1,800 deaths and 53,000 injuries requiring emergency room care. Approximately 1,600 fires are ignited, resulting in the destruction of 200 million square feet of the building stock, the equivalent of 133,000 single-family homes. Fire contributes $87 billion in property and business interruption loss, out of the total $191 billion in economic loss, with most of the rest coming from shakerelated building and content damage ($46 billion) and business interruption loss from water outages ($24 billion). Emergency response activities are depicted in detail, in an innovative grid showing activities versus time, a new format introduced in this study. © 2011, Earthquake Engineering Research Institute.
Lizundia B.,Rutherford Chekene |
Durphy S.,Rutherford Chekene |
Griffin M.,CCS Group |
Hortacsu A.,Applied Technology Council |
And 3 more authors.
NCEE 2014 - 10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering | Year: 2014
FEMA 154 Rapid Visual Screening of Buildings for Potential Seismic Hazards: A Handbook and the companion publication FEMA 155: Supporting Documentation provide a methodology for rapid visual screening of buildings. The Handbook provides a "sidewalk survey" approach that enables classification of buildings into two categories: those that appear to be adequately safe and those that may be seismically hazardous and should be evaluated in more detail by a design professional experienced in seismic evaluation and design. The First Edition of the Handbook was published in 1988, and it was updated to the Second Edition in 2002. The methodology has been used extensively throughout the United States by private sector organizations and government agencies to evaluate buildings, and it has served as a model for similar efforts in other countries. In a project funded by FEMA, the Applied Technology Council is updating both FEMA 154 and FEMA 155. Major enhancements in the Third Edition include improvements in the screening form; an added optional more detailed level of screening; updates of the scoring values; new reference guides for vertical and plan irregularities; additional building types; improved consideration of additions, adjacent structures, and retrofits; an optional electronic scoring methodology; new insight into risk; and more detailed discussion on how to run an effective screening program.
Anderson D.,University of Delaware |
Davidson R.A.,University of Delaware |
Himoto K.,Japan Building Research Institute |
Scawthorn C.,SPA Risk LLC |
Scawthorn C.,Kyoto University
Risk Analysis | Year: 2016
In this article, we develop statistical models to predict the number and geographic distribution of fires caused by earthquake ground motion and tsunami inundation in Japan. Using new, uniquely large, and consistent data sets from the 2011 Tōhoku earthquake and tsunami, we fitted three types of models-generalized linear models (GLMs), generalized additive models (GAMs), and boosted regression trees (BRTs). This is the first time the latter two have been used in this application. A simple conceptual framework guided identification of candidate covariates. Models were then compared based on their out-of-sample predictive power, goodness of fit to the data, ease of implementation, and relative importance of the framework concepts. For the ground motion data set, we recommend a Poisson GAM; for the tsunami data set, a negative binomial (NB) GLM or NB GAM. The best models generate out-of-sample predictions of the total number of ignitions in the region within one or two. Prefecture-level prediction errors average approximately three. All models demonstrate predictive power far superior to four from the literature that were also tested. A nonlinear relationship is apparent between ignitions and ground motion, so for GLMs, which assume a linear response-covariate relationship, instrumental intensity was the preferred ground motion covariate because it captures part of that nonlinearity. Measures of commercial exposure were preferred over measures of residential exposure for both ground motion and tsunami ignition models. This may vary in other regions, but nevertheless highlights the value of testing alternative measures for each concept. Models with the best predictive power included two or three covariates. © 2016 Society for Risk Analysis.
Porter K.A.,SPA Risk LLC |
Cobeen K.,Elstner Inc.
Structures Congress 2012 - Proceedings of the 2012 Structures Congress | Year: 2012
The San Francisco Community Action Plan for Seismic Safety (CAPSS), among other tasks, addressed the threat that regional earthquakes pose to 4,400 older, soft-story, highoccupancy woodframe residential buildings, like the apartment buildings that collapsed in the 1989 Loma Prieta earthquake. They house 8% of the city's population, in a city with a rental vacancy rate near 3%. A risk analysis was performed to estimate their postearthquake safety and repair costs under 4 scenarios and 4 what-if conditions. We used a method related to HAZUS-MH, but using detailed characteristics of 4 index buildings that served as proxies for the broader population. Post-earthquake safety was characterized in terms of ATC-20 (Applied Technology Council 1989 et seq.) tag color, plus a collapsed/not collapsed metric. Results were peer reviewed by respected engineers who added their own judgment. Results were presented to approximately 80 self-selected stakeholders, including tenants, owners, and other parties. The stakeholders identified, discussed, and selected policy recommendations that included a City ordinance for mandatory retrofit. It seems likely that the City will enact such an ordinance. If that outcome is deemed "success," we attribute it to four factors that might be emulated elsewhere. First, these buildings probably do represent a leading threat to the City's viability. The memory of the 1989 Loma Prieta earthquake and photographs of similar damage in 1906 are evidence of a real, ongoing threat. Second, the risk estimate focused on an important community value: safety tag color, rather than repair cost (though we presented both). Third, while acknowledging the many uncertainties involved, we limited our discussion of probabilities, focusing instead on realistic outcomes of a few realistic earthquakes that could occur any day, and certainly will occur eventually. Fourth, we made no policy recommendations, allowing the public (through the stakeholder committee) to determine what they thought was best for them and for the City. © ASCE 2012.
Porter K.,SPA Risk LLC
Earthquake Spectra | Year: 2010
The "cracking an open safe" methodology has been used to tabulate HAZUS-based seismic vulnerability as functions of structure-independent intensity, while avoiding iteration in the structural analysis. The vulnerability functions give mean damage factor (MDF, defined here as mean repair cost as a fraction of replacement cost) versus 5%-damped elastic spectral acceleration response at 0.3-second and 1.0-second periods, for every combination of occupancy type, model building type, design level, magnitude, distance, site soil classification, etc. Like HAZUS-MH, these prior seismic vulnerability functions give no estimate of uncertainty in damage factor. The coefficient of variation (COV) of damage factor is readily calculated by taking advantage of the fact that that at any level of excitation there is a probability mass function of damage state and an implicit distribution of repair cost conditioned on damage state. COV is calculated here for each combination of occupancy type, model building type, etc., tabulated alongside MDF, and the tables presented for public use at www.riskagora.org. It is found that a HAZUS-based COV generally decreases with increasing MDF (as has been observed using other analytical vulnerability methods), and the standard deviation of damage factor generally increases with increasing MDF. © 2010, Earthquake Engineering Research Institute.
Scawthorn C.R.,SPA Risk LLC
Earthquake Spectra | Year: 2011
Fire following earthquake (FFE) is a significant problem in California. Potential FFE were examined for the ShakeOut Scenario assuming a Mw 7.8 event on a morning in mid-November, with breezy (10 mph) low humidity conditions. FFE is a nonlinear process whose modeling does not have great precision - in many cases the only clear result is differentiation between a few small fires versus major conflagration. For the scenario, analysis indicates approximately 1,600 ignitions, with the central Los Angeles basin experiencing hundreds of large fires. Estimated loss is hundreds to perhaps a thousand lives, and approximately 200 million sq. ft. of residential and commercial building floor area, corresponding to a loss of perhaps as much as one hundred billion dollars virtually fully insured. Mitigation opportunities include construction of a seismically reliable regional saltwater pumping system to protect central Los Angeles, and automated gas shut-off devices in densely built areas. © 2011,Earthquake Engineering Research Institute.
Porter K.A.,SPA Risk LLC
9th US National and 10th Canadian Conference on Earthquake Engineering 2010, Including Papers from the 4th International Tsunami Symposium | Year: 2010
Owners of building portfolios in earthquake country have several data-related seismic risk mitigation concerns: Before an earthquake, they need to know the locations and seismic characteristics of their buildings to know which might pose a potential seismic risk. They also need the ability to assess and prioritize riskmitigation efforts, and to develop emergency response plans. Immediately after an earthquake, they need to know which buildings were most likely damaged to prioritize inspections, so as to mitigate the fatality risk in aftershocks, and may need to manage and perform the safety inspections. The US Federal Emergency Management Agency has developed a suite of software to assist that effort: Rapid Observation of Vulnerability and Estimation of Risk (ROVER) is free, opensource mobile software for building owners and risk managers to use to inventory buildings at risk from future earthquakes, monitor or analyze them for future seismic risk, and manage and perform post-earthquake safety assessments. Unlike paper forms (FEMA 154 and ATC-20), ROVER handles much of the data automatically, providing geolocation, automated soil and hazard lookup, watermarked digital photos, a web-accessible database, all controlled and managed by the user. ROVER integrates pre- and post-earthquake data with other risk-management software ShakeCast and HAZUS-MH. ROVER is free, with no licensing costs. It is open-source software, with human-readable source code available for examination and modification by co-developers, two of whom have already come forward, even before the software has been released. The software has been thoroughly tested and is endorsed by prominent members of the earthquake risk-mitigation community, building department officials, a state legislator, and other earthquake risk thought leaders.
SPA Risk LLC | Date: 2010-07-14
Computer application software for smart phones, portable computers, and Internet-accessible database servers, namely, software for collecting and managing data about the built environment and its attributes related to risk from natural and anthropologic disasters.