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.More →
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.More →
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.More →
24.01.2014 / Hazard / GEM GMPEs
A roadmap describing the process by which maps of the principal site parameters used in GMPEs could be prepared for global applicationMore →
Follow GEM's most active groups
To follow and unfollow groups you can also go to Personal Settings > Email Notifications to follow groups of your interest.
- Call for applications - EEFIT research grants
- The EEFIT Research Grant supports short-term projects that will benefit earthquake (and related hazards) disaster mitigation and post-disaster reconnaissance efforts.
- GEM Nexus restyling
- GEM Nexus has a new look and feel, fitting with new branding; other than that.. nothing changed!
- New Nexus group on Social Vulnerability & Resilience
- A project on Social Vulnerability and Resilience for GEM has recently taken off, in order to support GEM's mission of producing a holistic global earthquake risk model and tools to estimate the impact of earthquakes on economy and society.