Keith Porter

Keith Porter
University of Colorado Boulder | CUB · Department of Civil, Environmental and Architectural Engineering (CEAE)

PhD

About

98
Publications
22,594
Reads
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3,372
Citations
Additional affiliations
August 2007 - present
University of Colorado Boulder
Position
  • Professor

Publications

Publications (98)
Article
This article adapts a handful of procedures from performance‐based earthquake engineering for use in estimating the probability of liquefaction triggering. The resulting approach, defined as liquefaction fragility analysis (LFA), produces site‐specific fragility functions for liquefaction. These fragility functions incorporate site‐specific, system...
Article
Geotechnical liquefaction indices, such as the liquefaction potential index, are commonly used as proxies for the risk of liquefaction-induced damage at site or regional scales. However, these indices were developed based on surficial manifestations of soil liquefaction in the free field, and, as such, they have been shown to correlate better with...
Article
Full-text available
The precise description of reinforced concrete shear wall (RCSW) systems under severe dynamic loading remains a difficult research question owing to the intrinsically multi-scale underlying mechanisms, ranging from building’s irregularity to individual core walls, and even to the millimeter length-scales nonlinear shear over cracks and progressive...
Article
Recent research has highlighted the usefulness of cumulative absolute velocity [Formula: see text] in several contexts, including using the [Formula: see text] at the ground surface for earthquake early warning and using the [Formula: see text] at rock reference conditions for evaluation of the liquefaction risk facing structures. However, there ar...
Article
This study evaluates a variety of intensity measures (IMs) for predicting the liquefaction-induced residual settlement and tilt of shallow-founded structures. We use data from both numerical and physical (centrifuge) models of soil-foundation-structure systems. The relative quality of these IMs is quantified in terms of efficiency, sufficiency, and...
Conference Paper
Many procedures commonly used in geotechnical engineering rely on borehole data as input. While these procedures may characterize the uncertainty around their predictions, they typically do not provide guidance for evaluating uncertainty arising from imprecision or inaccuracy in measuring input parameters nor do they account for spatial variability...
Article
This paper presents models for predicting the residual and peak transient tilt of matfounded structures on liquefiable ground. First, the study presents a completely empirical model based on correlating residual tilt to settlement in case histories. Second, a semi-empirical model for residual tilt is developed based on an extensive numerical parame...
Research
Full-text available
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 non-linear analyses. The target is for a structural engineer with a Master’s level training...
Technical Report
Full-text available
Natural scientists, like many other experts, face challenges when communicating to people outside their fields of expertise. This is especially true when they try to communicate to those whose background, knowledge, and experience are far distant from that field of expertise. At a recent workshop, experts in risk communication offered insights into...
Conference Paper
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...
Conference Paper
The U.S. Federal Emergency Management Agency (FEMA) and the ROVER Development Consortium (RDC) have released a new version of software for communities to manage earthquake risk. FEMA’s Rapid Observation of Vulnerability and Estimation of Risk (ROVER) Version 2 is free mobile software for pre-and post-earthquake building screening that automates the...
Article
A comprehensive framework for potential failure modes (PFM) identification and quantification of concrete dams subjected to seismic excitation is presented. A quantifiable indicator of PFM is presented in the context of both linear and nonlinear analyses. As an illustrative example, a thin arch dam subjected to a set of ground motions at different...
Article
Second-generation performance-based earthquake engineering (PBEE-2) requires a library of component fragility functions to estimate probabilistic damage to a wide variety of building components. The present work draws on a large body of (mostly) post-earthquake reconnaissance and (some) post-earthquake survey observations of traction elevators to c...
Technical Report
Full-text available
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 non-linear analyses. The target is for a structural engineer with a Master’s level training...
Conference Paper
Full-text available
A set of guidelines was developed for the Global Earthquake Model (GEM), aiming to offer a practical, yet sufficiently accurate, analytical method for assessing the relationship between the ground shaking and the repair cost for a building class. The present work illustrates the methodology for a class of modern low-rise steel moment-resisting fram...
Article
Multiscale analysis technique became a successful remedy to complicated problems in which nonlinear behavior is linked with microscopic damage mechanisms. For efficient parallel multiscale analyses, hierarchical grouping algorithms (e.g., the two-level ‘coarse-grained’ method) have been suggested and proved superior over a simple parallelization. H...
Article
Large-scale loss-estimation procedures typically require vulnerability functions that relate ground motion to repair cost for each of many building classes, including classes that have not experienced earthquakes and so have no data on which to base an empirical vulnerability function. One fallback, analytical derivation, presents several challenge...
Conference Paper
Full-text available
The Global Earthquake Model (GEM) has commissioned the preparation of analytical seismic vulnerability guidelines for loss assessment of highrise buildings. The guidelines attempt to provide a practical method to assess the relationship between ground shaking and repair cost for a class of buildings, in face of the time, skill and computational cha...
Article
Notwithstanding powerful computational simulation methodologies available today, there remain significant challenges: the plane-section assumption of popular fiber models, the scale limitations of sophisticated microscopic methodologies such as particle-lattice models, and the difficulty in describing structural damage in actual physical terms. Her...
Book
Full-text available
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...
Conference Paper
Full-text available
The Global Earthquake Model (GEM; http://www.globalquakemodel.org/) is a grand effort to proffer a comprehensive open source tool for large scale loss assessment studies. For this to be accomplished, an analytical seismic vulnerability assessment methodology needs to be developed that links ground shaking with repair cost for a building class. The...
Article
Demand surge is understood to be a socioeconomic phenomenon associated with large-scale natural disasters. It is most commonly explained as higher repair costs resulting from higher labor wages and material prices after a large- versus small-scale disaster. This paper explores this explanation by developing quantitative models for the relative cost...
Conference Paper
Full-text available
The U.S. Geological Survey and several partners operate a program called Science Application for Risk Reduction (SAFRR) that produces (among other things) emergency planning scenarios for natural disasters. The scenarios show how science can be used to enhance community resiliency. The SAFRR Tsunami Scenario describes potential impacts of a hypothe...
Article
The cost of natural disasters continues to rise around the world, in part because of population growth, urbanization, and the pressures they place on land use. To reduce the vulnerability of infrastructure, especially existing infrastructure, will require that engineers bring more than technical capabilities to bear. Engineers need to know which me...
Article
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, high-occupancy 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...
Article
Fault trees have long been used to estimate failure risk in earthquakes, especially for nuclear power plants (NPPs). One interesting application is that one can assess and manage the probability that two facilities - a primary and backup - would be simultaneously rendered inoperative in a single earthquake. Another is that one can calculate the pro...
Chapter
Since the launch of the USGS’s Prompt Assessment of Global Earthquakes for Response (PAGER) system in fall of 2007, the time needed for the U.S. Geological Survey (USGS) to determine and comprehend the scope of any major earthquake disaster anywhere in the world has been dramatically reduced to less than 30 min. PAGER alerts consist of estimated sh...
Article
This paper presents a literature review of efforts to learn from earthquakes: collecting, archiving, and disseminating information. The emphasis is on primary sources, i.e., data-gathering instruments or investigations that include direct observation of earthquake effects. The study addresses seismology and geotechnical engineering; safety and dama...
Article
Demand surge is a process resulting in a higher cost to repair building damage after large disasters than to repair the same damage after a small disaster; this higher cost can be an additional 20% or more. It is of interest to insurers, regulators, property owners, and others. Despite its importance, demand surge has no standard definition or gene...
Article
The ShakeOut Scenario assessed earth-science impacts, physical damage, and socioeconomic impacts of a hypothetical M7.8 southern San Andreas Fault earthquake. Among many detailed studies were special studies of 12 lifelines, 7 of which were performed by panels of employees of the utilities at risk. Panels met for four hours. Panelists were presente...
Article
The USGS’s Multihazards Demonstration Project (MHDP) seeks to demonstrate how hazard science can improve a community’s resiliency to natural hazards. To do so, it must accurately but clearly communicate scientific concepts and findings to a wide variety of nonscientist stakeholders, many of whom are technical experts in their field primarily intere...
Article
We develop a global database of building inventories using taxonomy of global building types for use in near-real-time post-earthquake loss estimation and pre-earthquake risk analysis, for the U.S. Geological Survey's Prompt Assessment of Global Earthquakes for Response (PAGER) program. The database is available for public use, subject to peer revi...
Article
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 elast...
Article
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 risk-mitigation efforts, and to de...
Article
As part of a study for the City of San Francisco entitled Community Action Plan for Seismic Safety (CAPSS), we estimated the consequences of 4 large Bay Area earthquakes for large soft-story woodframe dwellings in San Francisco to inform City risk-management policy. A survey by the City's Department of Building Inspection found 2,800 residential wo...
Article
Full-text available
PH (626) 233-9758; email: keith@cohen-porter.net 3 Wiss, Janney, Elstner Associates Inc., Emeryville, CA; PH (510) 428-2907; email: kcobeen@wje.com 4 Tobin and Associates, Mill Valley, CA; PH (415) 380-9142; email: ABSTRACT San Francisco is in the process of doing something revolutionary: the City is heeding the warning of the moderate damage cause...
Conference Paper
The US Federal Emergency Management Agency and the US Geological Survey have developed a suite of free software for cities, building owners, and others to manage their seismic risk, before, during, and after earthquakes. FEMA's Rapid Observation of Vulnerability and Estimation of Risk (ROVER) is open-source software that operates on a Windows Mobil...
Article
Full-text available
The United Stated Geological Survey (USGS) Multi-Hazards Demonstration Project (MHDP) is preparing a new emergency-preparedness scenario, called ARkStorm, to address massive U.S. West Coast storms analogous to those that devastated California in 1861-62. Storms of this magnitude are projected to become more frequent and intense as a result of clima...
Article
In another work, the "open safe" of the HAZUS-MH methodology was cracked to create seismic vulnerability functions that honor all HAZUS-MH methodologies and data, yet that appear in the form of tables of mean casualty rates (indoor deaths and injuries as four fractions of total occupancy) versus a structure-independent intensity measure, in particu...
Article
Full-text available
A new methodology, called moment matching, to efficiently estimate repair costs of a building due to future earthquake excitation is presented. As well as excitation uncertainties, other uncertainties considered include those in the structural model and those in the capacity to resist damage and the unit repair costs of structural and nonstructural...
Article
The HAZUS-MH Technical Manual provides a method and data for calculating earthquake loss to ordinary buildings using in part the capacity spectrum method (CSM) of structural analysis, but it does not provide tabular results relating loss to structure-independent intensity measures such as S a(0.3 sec,5%) Or S a(1.0 sec,5%), and no procedure for doi...
Article
Among other phenomena, many insurance loss models estimate the increased losses in large-scale disasters--referred to here as catastrophes--compared to the losses in small-scale disasters. This amplification of loss has been traditionally and loosely called "demand surge," although there is a clear need for more specific terminology. Many factors h...
Article
Full-text available
This report describes a state-of-the-art performance-based earthquake engineering methodology that is used to assess the seismic performance of a four-story reinforced concrete (RC) office building that is generally representative of low-rise office buildings constructed in highly seismic regions of California. This “benchmark” building is consi...
Article
When a potentially damaging earthquake occurs, utility and other lifeline managers, emergency responders, and other critical users have an urgent need for information about the impact on their particular facilities so they can make appropriate decisions and take quick actions to ensure safety and restore system functionality. ShakeMap, a tool used...
Article
The Prompt Assessment of Global Earthquakes for Response (PAGER) System plays a primary alerting role for global earthquake disasters as part of the U.S. Geological Survey's (USGS) response protocol. We provide an overview of the PAGER system, both of its current capabilities and our ongoing research and development. PAGER monitors the USGS's near...
Article
The US Geological Survey is adding post-earthquake fatality estimation capability to its Prompt Assessment of Global Earthquakes for Response (PAGER) system. PAGER's goal is to inform early and rapid post-earthquake decisions about humanitarian assistance before ground-truth and news information can be acquired, and to examine hypothetical scenario...
Article
SUMMARY A state-of-the-art seismic performance assessment is illustrated through application to a reinforced- concrete moment-frame building designed per current (2003) building code provisions. Performance is quantified in terms of economic losses and collapse safety. The assessment includes site-specific seismic hazard analyses, nonlinear dynamic...
Article
New performance-based earthquake engineering methods developed by the Pacific Earthquake Engineering Research Center, the Applied Technology Council, and others include damage analysis at a highly detailed level, requiring the compilation of fragility functions for a large number of damageable generic structural and nonstructural components. This b...
Article
Full-text available
This study presents an estimate of the probability that a single earthquake could cause simultaneous operational failure of geographically disperse data centers operated by a California utility. Three facilities are considered: a grid control facility (denoted herein by GCF), a data processing facility (DPF), and a backup data facility (BDF) that c...
Article
Full-text available
The economic equivalent value of deaths and injuries in the 1994 Northridge earthquake has not previously been calculated, although number of injuries by category of treatment has. Using dollar-equivalent values for injuries accepted and used by the U.S. government for evaluating the cost-effectiveness of risk-mitigation efforts, the value of injur...
Article
Full-text available
The focus of this paper is to demonstrate the application of a recently developed Bayesian state estimation method to the recorded seismic response of a building and to discuss the issue of model selection. The method, known as the particle filter, is based on stochastic simulation. Unlike the well-known extended Kalman filter, it is applicable to...
Article
Full-text available
Performance-based earthquake engineering (PBEE) is a methodology that incorporates desired performance levels into the design process. Performance in PBEE can be economic (e.g., expected annual losses), or expressed in terms of operability and safety performance (e.g., expected downtime due to safety tagging and/or repair). These performance object...
Article
A technique is developed to estimate damage, loss, and post-earthquake operability for instrumented buildings shortly after the cessation of strong motion. The analysis modifies PEER’s second-generation performance-based earthquake engineering (PBEE-2) technique to account for the additional information that strong-motion instruments provide. In th...
Article
A technique is developed to model instrumented buildings with a second-generation performance-based earthquake engineering approach, producing a damage and loss estimate shortly after the cessation of strong motion. It estimates the likely locations of damage (including concealed structural damage), potentially saving the owner time and money by fo...
Article
Full-text available
A performance-based earthquake engineering methodology has recently been developed that quantifies building performance in terms of repair costs, life-safety risk, and loss of use (“dollars, deaths, and downtime”). The methodology is used to quantify the economic benefit (avoided future repair costs) of various detailed seismic retrofits, above-...
Article
The focus of this paper is Bayesian state and parameter estimation using nonlinear models. A recently developed method, the particle filter, is studied that is based on stochastic simulation. Unlike the well-known extended Kalman filter, the particle filter is applicable to highly nonlinear models with non-Gaussian uncertainties. Recently developed...
Technical Report
Full-text available
From 2002 to 2004 (years five and six of a ten-year funding cycle), the PEER Center organized the majority of its research around six testbeds. Two buildings and two bridges, a campus, and a transportation network were selected as case studies to “exercise” the PEER performance-based earthquake engineering methodology. All projects involved inte...
Conference Paper
The focus of this paper is to demonstrate the application of a recently developed Bayesian state estimation method to the recorded seismic response of a building. The method, known as the particle filter, is based on stochastic simulation. Unlike the well-known extended Kalman filter, it is applicable to highly nonlinear systems with non-Gaussian u...
Article
A seismic risk assessment is often performed on behalf of a buyer of commercial buildings in seismically active regions. One outcome of the as- sessment is that a probable maximum loss (PML) is computed. PML is of limited use to real-estate investors as it has no place in a standard financial analysis and reflects too long a planning period. We int...
Article
We examine seismic risk from the commercial real estate investor's viewpoint. We present a methodology to estimate the uncertain net asset value (NAV) of an investment opportunity considering market risk and seismic risk. For seismic risk, we employ a performance-based earthquake engineering methodology called assembly-based vulnerability (ABV). Fo...
Article
Full-text available
Motivation. A growing number of buildings have been instrumented to measure and record earthquake motions and to transmit these records to seismic-network data centers to be archived and disseminated for research purposes. At the same time, sensors are growing smaller, less expensive to install, and capable of sensing and transmitting other environ...
Article
In a modern performance-based earthquake engineering (PBEE) design framework, component fragility functions are used to relate parameters of structural response to damage. Since common structural response parameters are coupled to structural member properties, the usage of fragility functions in damage analysis after performing the structural analy...
Article
Full-text available
Estimation of structural response may be significantly affected by the representation of seismic ground motion uncertainty. A complete probabilistic presentation of ground motion can be constructed by specifying a stochastic model that depends on seismic source parameters. Alternatively, the ground motion uncertainty can be represented by adopting...
Conference Paper
The focus of this paper is real-time Bayesian state estimation using nonlinear models. A recently developed method, the particle filter, is studied that is based on Monte Carlo simulation. Unlike the well-known extended Kalman filter, it is applicable to highly nonlinear systems with non-Gaussian uncertainties. The particle filter is applied to a r...
Article
The Pacific Earthquake Engineering Research (PEER) Center’s second-generation performance-based earthquake engineering (PBEE) methodology is intended in part to model highway bridge performance in terms of collapse, closure, repair duration, speed or load limitations, and possibly other performance measures. Some of these are difficult to model, pa...
Conference Paper
This paper introduces a new Bayesian state-estimation methodology based on stochastic simulation of damage detection for nonlinear structural systems with non-Gaussian uncertainties. The new method uses a linear system with Gaussian uncertainties to build up an importance sampling probability density function (PDF). Samples are taken from the impor...
Article
This report presents a new methodology, called moment matching, of propagating the uncertainties in estimating repair costs of a building due to future earthquake excitation, which is required, for example, when assessing a design in performance-based earthquake engineering. Besides excitation uncertainties, other uncertain model variables are cons...
Article
A seismic risk assessment is often performed on behalf of a buyer of large commercial buildings in seismically active regions. One outcome of the assessment is that a probable maximum loss (PML) is computed. PML is of limited use to real-estate investors as it has no place in a standard financial analysis and reflects too long a planning period for...
Article
Full-text available
The focus of this report is real-time Bayesian state estimation using nonlinear models. A recently developed method, the particle filter, is studied that is based on Monte Carlo simulation. Unlike the well-known extended Kalman filter, it is applicable to highly nonlinear systems with non-Gaussian uncertainties. Recently developed techniques that i...
Article
Building owners make several important decisions in the hours after an earthquake occurs: whether to engage a structural engineer to inspect the building; what to tell investors, rating agencies, or other financial stakeholders; and how to assess the safety of tenants. A current research project seeks to develop the means to perform an automated, b...
Conference Paper
Most seismic risk assessments for economic decision-making of commercial buildings are based on a risk metric called probable maximum loss (PML) that is associated with losses from an earthquake shaking severity with a 500-year return period. For various reasons, PML is a poor metric for economic performance assessment. This paper introduces an ana...
Article
Various analytical approaches to performance-based earthquake engineering are in devel- opment. This paper summarizes the approach being pursued by the Pacific Earthquake Engineering Re- search (PEER) Center. It works in four stages: hazard analysis, structural analysis, damage analysis, and loss analysis. In the hazard analysis, one evaluates the...
Article
This paper examines the question of which sources of uncertainty most strongly affect the repair cost of a building in a future earthquake. Uncertainties examined here include spectral acceleration, ground-motion details, mass, damping, structural force-deformation behavior, building-component fragility, contractor costs, and the contractor's overh...
Article
Abstract A major component,of a building-specific seismic loss analysis is the estimation of repair costs in future earthquakes. A number of uncertain variables contribute to the uncertainty in these cost estimates. Among these are ground-shaking intensity, details of the ground motion, mass, damping, and force-deformation behavior, component fragi...
Article
A methodology is presented for making property investment decisions using loss analysis and the principles of decision analysis. It proposes that the investor choose among competing investment alternatives on the basis of the certainty equivalent of their net asset value which depends on the uncertain discounted future net income, uncertain disc...
Article
This report documents Tasks 4.1 and 4.5 of the CUREE-Caltech Woodframe Project. It presents a theoretical and empirical methodology for creating probabilistic relationships between seismic shaking severity and physical damage and loss for buildings in general, and for woodframe buildings in particular. The methodology, called assembly-based vulnera...