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Oakland, CA, United States

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. Source


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. Source


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. Source


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. Source


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. Source

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