EQECAT Inc.

Oakland, CA, United States

EQECAT Inc.

Oakland, CA, United States

Time filter

Source Type

Bozorgnia Y.,University of California at Berkeley | Hachem M.M.,Skidmore | Campbell K.W.,EQECAT Inc.
Earthquake Spectra | Year: 2010

This paper presents deterministic and probabilistic predictions of inelastic response spectra based on a comprehensive ground motion prediction equation (GMPE). Our analysis reveals that over a wide structural period range, the magnitude scaling for an inelastic system is higher than that for an elastic system, especially for ductility levels greater than 2 and magnitude greater than 6.5. Both deterministic and probabilistic hazard analyses show that the "equal displacement rule," to estimate inelastic displacement, is valid for small to moderate magnitudes and/or for low ductility levels. However, it underestimates inelastic deformation even for long period structures if the earthquake magnitude is large and the structure needs to sustain a large ductility. Our study shows that an inelastic GMPE can easily be implemented as part of standard probabilistic seismic hazard analysis (PSHA) packages to directly generate probabilistic hazard for inelastic response, avoiding possible over- or under-conservatism in approximating inelastic deformation from an elastic system. © 2010, Earthquake Engineering Research Institute.


Bozorgnia Y.,University of California at Berkeley | Hachem M.M.,Skidmore | Campbell K.W.,EQECAT Inc.
Earthquake Spectra | Year: 2010

This paper presents the process and fundamental results of a comprehensive ground motion prediction equation (GMPE, or "attenuation" relationship) developed for inelastic response spectra. We used over 3,100 horizontal ground motions recorded in 64 earthquakes with moment magnitudes ranging from 4.3-7.9 and rupture distances ranging from 0.1-199 km. For each record, we computed inelastic spectra for ductility ranging from one (elastic response) to eight. Our GMPE correlates inelastic spectral ordinates to earthquake magnitude, site-to-source distance, fault mechanism, local soil properties, and basin effects. The developed GMPE is used in both deterministic and probabilistic hazard analyses to directly generate inelastic - spectra. This is in contrast to developing "attenuation" relationships for elastic response spectra, carrying out a hazard analysis, and subsequently adopting approximate rules to derive inelastic response from elastic spectra. © 2010, Earthquake Engineering Research Institute.


Boore D.M.,U.S. Geological Survey | Campbell K.W.,EQECAT Inc. | Atkinson G.M.,University of Western Ontario
Bulletin of the Seismological Society of America | Year: 2010

We determined the stress parameter, Δσ, for the eight earthquakes studied by Atkinson and Boore (2006), using an updated dataset and a revised pointsource stochastic model that captures the effect of a finite fault. We consider four geometrical-spreading functions, ranging from 1/R at all distances to two- or threepart functions. The Δσ values are sensitive to the rate of geometrical spreading at close distances, with 1/R1.3 spreading implying much higher Δσ than models with 1=R spreading. The important difference in ground motions of most engineering concern, however, arises not from whether the geometrical spreading is 1/R1.3 or 1/R at close distances, but from whether a region of flat or increasing geometrical spreading at intermediate distances is present, as long as Δσ is constrained by data that are largely at distances of 100 km-800 km. The simple 1/R model fits the sparse data for the eight events as well as do more complex models determined from larger datasets (where the larger datasets were used in our previous ground motion prediction equations); this suggests that uncertainty in attenuation rates is an important component of epistemic uncertainty in ground-motion modeling. For the attenuation model used by Atkinson and Boore (2006), the average value of Δσ from the pointsource model ranges from 180 bars to 250 bars, depending on whether or not the stress parameter from the 1988 Saguenay earthquake is included in the average.We also find that Δσ for a given earthquake is sensitive to its moment magnitudeM, with a change of 0.1 magnitude units producing a factor of 1.3 change in the derived Δσ.


Campbell K.W.,EQECAT Inc. | Bozorgnia Y.,University of California at Berkeley
Earthquake Engineering and Structural Dynamics | Year: 2011

The JMA (Japan Meteorological Agency) seismic intensity scale has been used in Japan as a measure of earthquake ground shaking effects since 1949. It has traditionally been assessed after an earthquake based on the judgment of JMA officials. In 1996 the scale was revised as an instrumental seismic intensity measure (IJMA) that could be used to rapidly assess the expected damage after an earthquake without having to conduct a survey. Since its revision, Japanese researchers have developed several ground motion prediction equations (GMPEs) for IJMA using Japanese ground motion data. In this paper, we develop a new empirical GMPE for IJMA based on the strong motion database and functional forms used to develop similar GMPEs for peak response parameters as part of the PEER (Pacific Earthquake Engineering Research Center) Next Generation Attenuation (NGA) project. We consider this relationship to be valid for shallow crustal earthquakes in active tectonic regimes for moment magnitudes (M) ranging from 5.0 up to 7.5-8.5 (depending on fault mechanism) and rupture distances ranging from 0 to 200km. A comparison of this GMPE with relationships developed by Japanese researchers for crustal and shallow subduction earthquakes shows relatively good agreement among all of the relationships at M 7.0 but relatively poor agreement at small magnitudes. Our GMPE predicts the highest intensities at small magnitudes, which together with research on other ground motion parameters, indicates that it provides conservative or upwardly biased estimates of IJMA for M<5.5. © 2010 John Wiley & Sons, Ltd.


Campbell K.W.,EQECAT Inc. | Bozorgnia Y.,University of California at Berkeley
Earthquake Spectra | Year: 2010

Cumulative absolute velocity (CAV), defined as the integral of the absolute acceleration time series, has been used as an index to indicate the possible onset of structural damage to nuclear power plant facilities and liquefaction of saturated soils. However, there are very few available ground motion prediction equations for this intensity measure. In this study, we developed a new empirical prediction equation for the horizontal component of CAV using the strong motion database and functional forms that were used to develop similar prediction equations for peak response parameters as part of the PEER Next Generation Attenuation (NGA) Project. We consider this relationship to be valid for magnitudes ranging from 5.0 up to 7.5-8.5 (depending on fault mechanism) and distances ranging from 0-200 km. We found the interevent, intra-event, and intracomponent standard deviations from this relationship to be smaller than any intensity measure we have investigated thus far. © 2010, Earthquake Engineering Research Institute.


Campbell K.W.,EQECAT Inc. | Bozorgnia Y.,University of California at Berkeley
Earthquake Spectra | Year: 2012

Cumulative absolute velocity (CAV) has been proposed as an instrumental index to quantify the potential earthquake damage to structures. We explore this idea further by developing a relationship between the standardized version of CAV and the Japan Meteorological Agency (JMA) and modified Mercalli (MMI) instrumental seismic intensities in order to correlate standardized CAV with the qualitative descriptions of damage in the corresponding macroseismic intensity scales. Such an analysis statistically identifies the threshold values of standardized CAV associated with the onset of damage to buildings of good design and construction inherent in these scales. Based on these results, we suggest that CAV might be used to rapidly assess the potential damage to a general class of conventional structures after an earthquake. However, other ground motion or damage-related parameters might be better suited to quantifying the potential damage to structures of a specific type and size. © 2012, Earthquake Engineering Research Institute.


Campbell K.W.,EQECAT Inc. | Bozorgnia Y.,University of California at Berkeley
Earthquake Spectra | Year: 2012

Arias intensity (AI) and cumulative absolute velocity (CAV) have been proposed as instrumental intensity measures that can incorporate the cumulative effects of ground motion duration and intensity on the response of structural and geotechnical systems. In this study, we have developed a ground motion prediction equation (GMPE) for the horizontal component of AI in order to compare its predictability to a similar GMPE for CAV. Both GMPEs were developed using the same strong motion database and functional form in order to eliminate any bias these factors might cause in the comparison. This comparison shows that AI exhibits significantly greater amplitude scaling and aleatory uncertainty than CAV. The smaller standard deviation and less sensitivity to amplitude suggests that CAV is more predictable than AI and should be considered as an alternative to AI in engineering and geotechnical applications where the latter intensity measure is traditionally used. © 2012, Earthquake Engineering Research Institute.


Campbell K.W.,EQECAT Inc.
Geotechnical, Geological and Earthquake Engineering | Year: 2011

The widespread application of the hybrid empirical method (HEM) has made it a viable approach for developing ground motion prediction equations (GMPEs) in regions where there are few strong motion recordings but ample weak motion data from small-to-moderate magnitude earthquakes. The HEM uses empirical estimates of ground motion in a host region to provide estimates of ground motion in a target region by taking into account differences in source, path, and site effects between the two regions. Empirical ground motion estimates in the host region are transferred to the target region using adjustment factors that are calculated from regionally constrained seismological models using stochastic simulation. In this paper, I discuss the issues and demonstrate the epistemic uncertainty involved in applying the HEM using an example application to eastern North America (ENA) based on the Campbell-Bozorgnia NGA GMPE for western North America (WNA) and updated seismological models for ENA. © Springer Science+Business Media B.V. 2011.


Kim Y.,EQECAT Inc. | Kang W.-H.,University of Western Sydney
Reliability Engineering and System Safety | Year: 2013

Civil infrastructures such as transportation, water supply, sewers, telecommunications, and electrical and gas networks often establish highly complex networks, due to their multiple source and distribution nodes, complex topology, and functional interdependence between network components. To understand the reliability of such complex network system under catastrophic events such as earthquakes and to provide proper emergency management actions under such situation, efficient and accurate reliability analysis methods are necessary. In this paper, a non-simulation-based network reliability analysis method is developed based on the Recursive Decomposition Algorithm (RDA) for risk assessment of generic networks whose operation is defined by the connections of multiple initial and terminal node pairs. The proposed method has two separate decomposition processes for two logical functions, intersection and union, and combinations of these processes are used for the decomposition of any general system event with multiple node pairs. The proposed method is illustrated through numerical network examples with a variety of system definitions, and is applied to a benchmark gas transmission pipe network in Memphis TN to estimate the seismic performance and functional degradation of the network under a set of earthquake scenarios. © 2012 Elsevier Ltd.


Campbell K.W.,EQECAT Inc.
Bulletin of the Seismological Society of America | Year: 2014

Ground-motion models (GMMs) and ground-motion adjustment factors developed using the hybrid empirical method (HEM) are used in seismic-hazard analyses throughout the world as an alternative to GMMs developed from the more traditional empirical and simulation methods. The HEM uses the ratio of stochastic ground-motion simulations between a target and host region to adjust empirical GMMs from the host region to use in the target region. The HEM is used primarily in regions where strong-motion data are sparse or exist only for small-magnitude earthquakes. The most common application of the HEM has been in the development of GMMs for eastern North America (ENA), two of which were used in the 2008 U.S. national seismic-hazard maps, but the method also has been used to develop or adjust GMMs in many other regions of the world. A comparison of four ENA GMMs developed using the HEM and a fifth developed using the closely related referenced empirical approach show that they fall into three distinct groups based on differences in the methods, models, and parameters used to calculate the host-to-target adjustment factors, and on differences in the selection of the host empirical ground-motion models. A different set of groups are implied from the aleatory variability models. General guidance is provided to aid the user in the selection and weighting of the five GMMs for application in seismic-hazard analysis.

Loading EQECAT Inc. collaborators
Loading EQECAT Inc. collaborators