Exposure & Vulnerability

GEM Vulnerability (physical)

GEM Vulnerability (physical)

We are working on the 'Seismic Vulnerability Development Guidelines and Seismic Vulnerability Functions' project; the largest-ever public effort to understand the seismic vulnerability of buildings around the world. The project has two central objectives: to develop procedures for deriving vulnerability functions, and to actually implement those procedures and produce seismic vulnerability functions for a wide variety of building types. Read more..

If you would like to get in touch with us, contact Keith Porter, the project lead @ keith.porter[at]colorado.edu

Group Posts

Through these posts we share our work in the context of GEM. Sometimes these are status updates, sometimes these are presentations we gave and sometimes these are reports or other documents, but it always work-in-progress.
We are very much interested in receiving your feedback and ideas, so please do comment on our posts and/or rate the comments of others.
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20.04.2014 / Exposure & Vulnerability / GEM Vulnerability (physical)
Backup copy of the FEMA P-695 far-field ground motions, for use in applying structural analysis method 3 of the GEM analytical vulnerability guidelines for highrise buildings.
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26.03.2014 / Exposure & Vulnerability / GEM Vulnerability (physical)
The near final draft version of the Guidelines for Empirical Vulnerability Assessment are now available. This document aims to provide a simple but flexible guide for the construction of vulnerability and fragility curves from post-earthquake loss and damage survey data. It provides guidance on the preparation of empirical data for the construction of the vulnerability relationships and for the identification of errors and biases in the data. It proposes a framework, where a number of statistical modelling techniques and ground motion intensity measures can be used to represent the empirical data, and diagnostic tools for assessing the optimal functional form for the relationships. It is recognised that the statistical analysis understanding of users of the guidelines may vary, hence two levels of statistical approaches for constructing empirical fragility and vulnerability functions are proposed that include procedures of increasing complexity. To facilitate the use of the guidelines, the code and commands required for the implementation of the described statistical models are provided for the open-source software R (2008). Example applications of the guidelines, where each step of the assessment is illustrated for empirical datasets from Italian, Australian, Greek and New Zealand earthquakes, are provided in the appendices. The current version of the guidelines is being reviewed by two independent international experts. The final version of this document will be published before the release of the OpenQuake-platform.
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06.03.2014 / Exposure & Vulnerability / GEM Vulnerability (physical)
Guidelines (GEM-ASV) for developing analytical seismic vulnerability functions are offered for use within the framework of the Global Earthquake Model (GEM). Emphasis is on low/mid-rise buildings and cases where the analyst has the skills and time to perform nonlinear analyses. The target is for a structural engineer with a Master’s level training and the ability to create simplified nonlinear structural models to be able to determine the vulnerability functions pertaining to structural response, damage or loss for any single structure, or for a class of buildings defined by the GEM Taxonomy level 1 attributes. At the same time, sufficient flexibility is incorporated to allow full exploitation of cutting-edge methods by knowledgeable users. The basis for this effort consists of the key components of the state-of-art PEER/ATC-58 methodology for loss assessment, incorporating simplifications for reduced effort and extensions to accommodate a class of buildings rather than a single structure, and multiple damage states rather than collapse only considerations. To inject sufficient flexibility into the guidelines and accommodate a range of different user needs and capabilities, a distinct hierarchy of complexity (and accuracy) levels has been introduced for (a) defining index buildings, (b) modeling and (c) analyzing. Sampling-wise, asset classes may be represented by random or Latin hypercube sampling in a Monte Carlo setting. For reduced-effort representations of inhomogeneous populations, simple stratified sampling is advised, where the population is partitioned into a number of appropriate subclasses, each represented by one “index” building. Homogeneous populations may be approximated using a central index building plus 2k additional high/low observations in each of k dimensions (properties) of interest. Structural representation of index buildings may be achieved via typical 2D/3D element-by-element models, simpler 2D story-by-story (stick) models or an equivalent SDOF system with a user-defined capacity curve. Finally, structural analysis can be based on variants of Incremental Dynamic Analysis (IDA) or Nonlinear Static Procedure (NSP) methods. A similar structure of different level of complexity and associated accuracy is carried forward from the analysis stage into the construction of fragility curves, damage to loss function definition and vulnerability function derivation. In all cases, the goal is obtaining useful approximations of the local story drift and absolute acceleration response to estimate structural, non-structural and content losses. Important sources of uncertainty are identified and propagated incorporating the epistemic uncertainty associated with simplifications adopted by the user. The end result is a set of guidelines that seamlessly fits within the GEM framework to allow the generation of vulnerability functions for any class of low/mid-rise buildings with a reasonable amount of effort by an informed engineer. Three illustrative examples are presented for the assessment of reinforced-concrete moment-resisting frames with masonry infills, unreinforced masonry structures and ductile steel moment-resisting frames. The current version of the guidelines is being reviewed by two independent international experts. The final version of this document will be published before the release of the OpenQuake-platform.
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17.01.2014 / Exposure & Vulnerability / GEM Vulnerability (physical)
We share the findings of two separate expert judgment surveys on structural collapse fragility estimation carried out by the Earthquake Engineering Research Institute (EERI), with financial support from the GEM Foundation and the U.S. Geological Survey (USGS). In the first elicitation in September 2012 in Lisbon, Portugal, thirteen experts from eight countries provided their engineering judgments on the structural collapse fragility of six masonry (MS) and six reinforced concrete construction (RC) types that are commonly found in earthquake prone countries around the world. The second elicitation workshop was conducted in Oakland, California in May 2013. The impetus for the Oakland workshop was to derive collapse-fragility parameters for several vulnerable construction typologies within the United States, by soliciting engineering judgments from the domain experts on these types. This exercise was funded primarily through a USGS grant, with additional support provided by the GEM Foundation.
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12.12.2013 / Exposure & Vulnerability / GEM Vulnerability (physical)
Recent extensive literature review, which has been conducted within the framework of the development of the “GEM Guide for Selecting of Existing Analytical Fragility Curves and Compilation of the Database”, has shown that often fragility functions are generated using simplified assumptions to reduce the calculation efforts. Some of the most widely implemented simplifications are: the use of default values to model structural characteristics-related parameters; the use of 2-D models, and ignoring, for the case of infilled RC buildings, the contribution of infill panels in the seismic response by modelling them as bare frame structures. However, these assumptions may highly decrease the reliability and accuracy of the obtained results introducing important epistemic uncertainty in the fragility function construction process. The present document is devoted to provide, for GEM guidelines users, details on the effect that the choice of building capacity-related parameters and their expected uncertainty, might have on the results of vulnerability and fragility functions derivation and, hence, steer users towards a better quantification of such uncertainties. The document presents the result of investigation on the sensitivity of structure response to variation in structural characteristics-related parameters’ values (i.e. in terms of mechanical properties, geometric configuration and dimension, structural details) and in mathematical modelling (i.e. completeness of models). The classes of structures considered are low-ductility RC buildings designed according to earlier seismic codes, and which are in general characterized by poor quality of materials, workmanship and detailing. This building class constitutes one of the largest portions of existing residential building stock in earthquake prone countries.
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12.12.2013 / Exposure & Vulnerability / GEM Vulnerability (physical)
Guidelines for developing analytical seismic vulnerability functions are offered for use within the framework of the Global Earthquake Model (GEM). Emphasis is on low/mid-rise buildings and cases where the analyst has the skills and time to perform nonlinear analyses. The target is for a structural engineer with a Master’s level training and the ability to create simplified nonlinear structural models to be able to determine the vulnerability functions pertaining to structural response, damage or loss for any single structure, or for a class of buildings defined by the GEM Taxonomy level 1 attributes. At the same time, sufficient flexibility is incorporated to allow full exploitation of cutting-edge methods by knowledgeable users. The basis for this effort consists of the key components of the state-of-art PEER/ATC-58 methodology for loss assessment, incorporating simplifications for reduced effort and extensions to accommodate a class of buildings rather than a single structure, and multiple damage states rather than collapse only considerations. To inject sufficient flexibility into the guidelines and accommodate a range of different user needs and capabilities, a distinct hierarchy of complexity (and accuracy) levels has been introduced for (a) defining index buildings, (b) modeling and (c) analyzing. Sampling-wise, asset classes may be represented by random or Latin hypercube sampling in a Monte Carlo setting. For reduced-effort representations of inhomogeneous populations, simple stratified sampling is advised, where the population is partitioned into a number of appropriate subclasses, each represented by one “index” building. Homogeneous populations may be approximated using a central index building plus 2k additional high/low observations in each of k dimensions (properties) of interest. Structural representation of index buildings may be achieved via typical 2D/3D element-by-element models, simpler 2D story-by-story (stick) models or an equivalent SDOF system with a user-defined capacity curve. Finally, structural analysis can be based on variants of Incremental Dynamic Analysis (IDA) or Nonlinear Static Procedure (NSP) methods. A similar structure of different level of complexity and associated accuracy is carried forward from the analysis stage into the construction of fragility curves, damage to loss function definition and vulnerability function derivation. In all cases, the goal is obtaining useful approximations of the local story drift and absolute acceleration response to estimate structural, non-structural and content losses. Important sources of uncertainty are identified and propagated incorporating the epistemic uncertainty associated with simplifications adopted by the user. The end result is a set of guidelines that seamlessly fits within the GEM framework to allow the generation of vulnerability functions for any class of low/mid-rise buildings with a reasonable amount of effort by an informed engineer. Three illustrative examples are presented for the assessment of reinforced-concrete moment-resisting frames with masonry infills, unreinforced masonry structures and ductile steel moment-resisting frames.
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09.12.2013 / Exposure & Vulnerability / GEM Vulnerability (physical)
The attached document provides analysis of experts' responses to all the seed questions that ultimately were used to estimate the Cooke's weight. Each expert could receive different weight depending upon the construction types for which he/she is pooled. For eliciting judgments for the collapse fragility problem, it was important to ensure that the seed question represented a) a broad range of earthquake resistance design and construction topics, and the state-of-the-art and practices in different parts of the world, b) performance of selected building types during strong shaking in different earthquakes, c) experimental and analytical research studies on the collapse fragility problem, and d) the experts' ability to evaluate and draw statistical judgments based on field data.
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09.12.2013 / Exposure & Vulnerability / GEM Vulnerability (physical)
This document summarizes the mathematical procedure employed in Cooke's method and the findings of an expert elicitation workshop in which a dozen earthquake-engineering professionals from around the world were engaged to estimate seismic collapse fragility for generic construction types. Development of seismic collapse fragility-functions was accomplished by combining their judgments using weights derived from Cooke’s method.
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22.04.2013 / Exposure & Vulnerability / GEM Vulnerability (physical)
This document reviews existing empirical vulnerability and fragility functions worldwide in terms of their characteristics, data sources and statistical modelling techniques. A qualitative rating system is described and applied to all reviewed functions to aid users to choose between existing functions for use in seismic risk assessments.
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08.04.2013 / Exposure & Vulnerability / GEM Vulnerability (physical)
The GEM Vulnerability Consortium offers a draft analytical vulnerability guideline document for internal and community review. It is a simplified version of the PEER 2nd-generation performance-based earthquake engineering methodology, but one that treats building classes through analyses of 1, 3, or 7 representative index buildings in the class. It demonstrates the integration of structural and nonstructural repair costs.
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07.03.2013 / Exposure & Vulnerability / GEM Vulnerability (physical)
This report features a procedure for the OpenQuake software suite to offer an available vulnerability function for any acceptable set of attributes that the user specifies for a particular building category. It also provides general guidelines on how to submit the vulnerability or fragility functions to the GEM physical vulnerability database. We look forward to your feedback; do leave your comments immediately below.
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07.03.2013 / Exposure & Vulnerability / GEM Vulnerability (physical)
The following Earthquake Spectra article details the methodology for estimating earthquake-induced direct economic losses using various input dataset/parameters such as country-specific gross domestic product, population exposure, estimates on shaking intensity and country- or region-specific empirical model parameters. The document also provide some comparative analysis of model-estimated losses vs. recorded losses for series of recent large earthquakes. The modeling parameters can be easily accessed here (http://pubs.usgs.gov/of/2011/1116/). Please contact: Kishor Jaiswal (kjaiswal@usgs.gov) for any feedback/comments or query.
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12.12.2012 / Exposure & Vulnerability / GEM Vulnerability (physical)
This document was written for GEM1 in 2009. It proposes a variety of file formats for exchanging hazard, damage, and loss data. It includes CSV file formats for fragility and vulnerability functions. For example, see generic fragility table format FRA02 and somewhat generic vulnerability table format VUL06 on pages 39 and 46, respectively, and casualty-rate table VUL07 on pg 58. We can revise it in light of the literature we have compiled in year-1.
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04.12.2012 / Exposure & Vulnerability / GEM Vulnerability (physical)
Minor revision to contents vulnerability guidelines to clarify seismic response coefficient CS; response vector; collapse fragility; correct typos; use GEM report template; expand sample calc.
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28.11.2012 / Exposure & Vulnerability / GEM Vulnerability (physical)
This pptx proposes a 3-level approach to propagating uncertainty in analytical vulnerability functions that accommodates different levels of effort on the part of the analyst through the analysis of 1, 3, or 7 index buildings. Already internally developed and reviewed by University of Colorado and Stanford, and externally reviewed by Crowley and Bazzurro, we offer it here for general consideration and feedback from the GEM community. Please correspond with Porter.
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17.11.2012 / Exposure & Vulnerability / GEM Vulnerability (physical)
Draft guidelines for the derivation of content vulnerability functions, for general review and comment.
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03.08.2012 / Exposure & Vulnerability / GEM Vulnerability (physical)
In the first comprehensive application of Cooke’s structured elicitation process in the field of seismic vulnerability estimation, EERI is assisting the GEM Vulnerability Consortium (GVC) to develop generic seismic collapse fragility functions for selected global construction types. In particular, experts will focus on concrete and masonry building types. In order to elicit and combine multiple judgments, the GEM Co-PIs are exploring the application of Cooke’s method and EERI is assisting by organizing a small workshop of experts at the 15WCEE in Lisbon.
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23.02.2012 / Exposure & Vulnerability / GEM Vulnerability (physical)
This Powerpoint file briefly summarizes the GEM Vulnerability Consortium's (GVC) status as of June 2011, as presented in Beijing. It is provided here because it contains a review of the project objectives, and may be useful to a GVC team member for a presentation.
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19.02.2012 / Exposure & Vulnerability / GEM Vulnerability (physical)
Repair-cost vulnerability functions with mean and coefficient of variation of repair cost conditioned on Sa(1.0 sec, 5%), for all combinations of US HAZUS-MH model building type, code era including special, and occupancy. Only the subset calculated with M = 7 is presented in this database. It is published here as part of the GEM Vulnerability Consortium's effort to compile existing vulnerability functions.
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04.12.2011 / Exposure & Vulnerability / GEM Vulnerability (physical)
This is a pdf of the Powerpoint presented by Porter and So at the 2-4 Dec 2011 meeting in Menlo Park, CA, to review the GEM global components.
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04.12.2011 / Exposure & Vulnerability / GEM Vulnerability (physical)
This 1-page document specified procedures for peer review of our vulnerability guidelines. It has been reviewed by the project team of the GEM Vulnerability Consortium. We welcome comments from the GEM community on the procedures through December 2011.
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27.10.2011 / Exposure & Vulnerability / GEM Vulnerability (physical)
The GEM Global Vulnerability Consortium offers for review and commentary a draft rating system for vulnerability and fragility functions. Please provide any comments to Keith Porter by 1 Dec 2011.
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