scholarly journals Using 1 -D and 2-D modelling of ground motion for seismic zonation criteria: results for the city of Rome

1995 ◽  
Vol 38 (5-6) ◽  
Author(s):  
A. Rovelli ◽  
L. Malagnini ◽  
A. Caserta ◽  
F. Marra
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Response Spectra ◽  
Ground Acceleration ◽  
Seismic Zonation ◽  
Geological Information ◽  
Horizontal Ground Motion ◽  
Numerical Generation ◽  
Flux Response ◽  
The City

The geological information collected in the last years by the Istituto Nazionale di Geofisica for the city of Rome is used to construct 1- and 2-D models of the nearsurface structure. These models are the basis for the numerical generation of synthetic accelerograms which can simulate the horizontal ground motion (SH waves) produced in the different areas of the city by a large (M ? 7) potential earthquake 100 km away in Central Apennines. The proposed methodology yields earthquake engineering parameters (peak ground acceleration and velocity, Arias intensity, energy flux, response spectra) whose spatial variations are consistent with the damage distribution caused by the strongest earthquakes felt in Rome during its long history. Based on the macroseismic inforination and the results of the numerical simulations, general criteria for seismic zonation of the city of Rome are proposed.

scholarly journals Assessment of potential strong ground motions in the city of Rome

1994 ◽  
Vol 37 (6) ◽  
Author(s):  
A. Rovelli ◽  
A. Caserta ◽  
L. Malagnini ◽  
F. Marra
Keyword(s):  
Ground Motion ◽  
Seismic Energy ◽  
Response Spectra ◽  
Arias Intensity ◽  
Ground Acceleration ◽  
Finite Difference Technique ◽  
Time Histories ◽  
Horizontal Ground Motion ◽  
The City ◽  
Simulated Time

A methodology is used which combines stochastic generation of random series with a finite-difference technique to estimate the expected horizontal ground motion for the city of Rome as induced by a large earthquake in the Central Apennines. In this approach, source properties and long-path propagation are modelled through observed spectra of ground motion in the region, while the effects of the near-surface geology in the city are simulated by means of a finite-difference technique applied to 2-D models including elastic and anelastic properties of geologic materials and topographic variations. The parameters commonly used for earthquake engineering purposes are estimated from the simulated time histories of horizontal ground motion. We focus our attention on peak ground acceleration and velocity, and on the integral of the squared acceleration and velocity (that are proportional to the Arias intensity and seismic energy flux, respectively). Response spectra are analyzed as well. Parameter variations along 2-D profiles visualize the effects of the small-scale geological heterogeneities and topography irregularities on ground motion in the case of a strong earthquake. Interestingly, the largest amplification of peak ground acceleration and Arias intensity does not necessarily occur at the same sites where peak ground velocity and flux of seismic energy reach their highest values, depending on the frequency band of amplification. A magnitude 7 earthquake at a distance of 100 km results in peak ground accelerations ranging from 30 to 70 gals while peak ground velocities are estimated to vary from 5 to 7 cm/s; moreover, simulated time histories of horizontal ground motion yield amplitudes of 5% damped pseudovelocity response spectra as large as 15-20 cm/s for frequencies from 1to 3 Hz. In this frequency band, the mean value is 7 cm/s for firm sites and ranges from 10 to 13 cm/s for soil sites. All these results are in good agreement with predictions based on regressions of Italian and Western North American data.

NGA-West2 Models for Ground Motion Directionality

2014 ◽  
Vol 30 (3) ◽  
pp. 1285-1300 ◽  
Author(s):  
Shrey K. Shahi ◽  
Jack W. Baker
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Response Spectra ◽  
Engineering Research ◽  
The Pacific ◽  
Horizontal Ground Motion ◽  
Motion Directionality ◽  
The Relationship

The NGA-West2 research program, coordinated by the Pacific Earthquake Engineering Research Center (PEER), is a major effort to produce refined models for predicting ground motion response spectra. This study presents new models for ground motion directionality developed as part of that project. Using a database of recorded ground motions, empirical models have been developed for a variety of quantities related to direction-dependent spectra. A model is proposed for the maximum spectral acceleration observed in any orientation of horizontal ground motion shaking ( Sa RotD100), which is formulated as a multiplicative factor to be coupled with the NGA-West2 models that predict the median spectral accelerations over all orientations ( Sa RotD50). Models are also proposed for the distribution of orientations of the Sa RotD100 value, relative to the fault and the relationship between Sa RotD100 orientations at differing periods. Discussion is provided regarding how these results can be applied to perform seismic hazard analysis and compute realistic target spectra conditioned on different parameters.

scholarly journals Preliminary results of ground-motion characteristics

2012 ◽  
Vol 55 (4) ◽  
Author(s):  
Francesca Bozzoni ◽  
Carlo Giovanni Lai ◽  
Laura Scandella
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Response Spectrum ◽  
Field Tests ◽  
Response Spectra ◽  
Ground Acceleration ◽  
Preliminary Results ◽  
Emilia Earthquake ◽  
Particle Orbit ◽  
2012 Emilia Earthquake

The preliminary results are presented herein for the engineering applications of the characteristics of the ground motion induced by the May 20, 2012, Emilia earthquake. Shake maps are computed to provide estimates of the spatial distribution of the induced ground motion. The signals recorded at the Mirandola (MRN) station, the closest to the epicenter, have been processed to obtain acceleration, velocity and displacement response spectra. Ground-motion parameters from the MRN recordings are compared with the corresponding estimates from recent ground-motion prediction equations, and with the spectra prescribed by the current Italian Building Code for different return periods. The records from the MRN station are used to plot the particle orbit (hodogram) described by the waveform. The availability of results from geotechnical field tests that were performed at a few sites in the Municipality of Mirandola prior to this earthquake of May 2012 has allowed preliminary assessment of the ground response. The amplification effects at Mirandola are estimated using fully stochastic site-response analyses. The seismic input comprises seven actual records that are compatible with the Italian code-based spectrum that refers to a 475-year return period. The computed acceleration response spectrum and the associated dispersion are compared to the spectra calculated from the recordings of the MRN station. Good agreement is obtained for periods up to 1 s, especially for the peak ground acceleration. For the other periods, the spectral acceleration of the MRN recordings exceeds that of the computed spectra.<br />

Engineering observations on ground motion at the Van Norman Complex after the 1994 Northridge earthquake

1996 ◽  
Vol 86 (1B) ◽  
pp. S333-S349 ◽  
Author(s):  
J. P. Bardet ◽  
C. Davis
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Low Frequency ◽  
Strong Motion ◽  
Response Spectra ◽  
Vertical Acceleration ◽  
Northridge Earthquake ◽  
Peak Acceleration ◽  
Geotechnical Earthquake Engineering ◽  
1994 Northridge Earthquake

Abstract During the 1994 Northridge earthquake, the Van Norman Complex yielded an unprecedented number of recordings with high acceleration, in the close proximity of the fault rupture. These strong-motion recordings exhibited the pulses of the main event. One station recorded the largest velocity ever instrumentally recorded (177 cm/sec), resulting from a 0.86 g peak acceleration with a low frequency. Throughout the complex, the horizontal accelerations reached peak values ranging from 0.56 to 1.0 g, except for the complex center, where the peak acceleration did not exceed 0.43 g. The vertical acceleration reached maximum peak values comparable with those of the horizontal acceleration. The acceleration response spectra in the longitudinal and transverse directions were significantly different. Such a difference, which is not yet well documented in the field of geotechnical earthquake engineering, indicates that the amplitude and frequency content of the ground motion was directionally dependent in the Van Norman Complex.

Response spectral matching of horizontal ground motion components to an orientation-independent spectrum (RotDnn)

2020 ◽  
pp. 875529302097098
Author(s):  
Luis A Montejo
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Time History ◽  
Response Spectra ◽  
Major Axis ◽  
Component Level ◽  
Nonlinear Characteristics ◽  
Target Spectrum ◽  
Horizontal Ground Motion ◽  
Median Spectrum

This article presents a methodology to spectrally match two horizontal ground motion components to an orientation-independent target spectrum (RotDnn). The algorithm is based on the continuous wavelet transform decomposition and iterative manipulation of the two horizontal components of a seed record. The numerical examples presented follow current ASCE/SEI 7 specifications and therefore maximum-direction spectra (RotD100) are used as target for the match. However, the proposed methodology can be used to match other RotDnn spectra, like the median spectrum (RotD50). It is shown that with the proposed methodology the resulting RotDnn from the modified horizontal components closely match the smooth target RotDnn spectrum, while the response spectrum for each horizontal component continue to exhibit a realistic jagged behavior. The response spectra variability at the component level within suites of spectrally matched motions was found to be of the same order than the variability measured in suites composed of amplitude scaled records. Moreover, the spectrally matched records generated preserved most of the characteristics of the seed records, including the nonlinear characteristics of the time history traces and the period-dependent major axis orientations.

NGA-West2 Research Project

2014 ◽  
Vol 30 (3) ◽  
pp. 973-987 ◽  
Author(s):  
Yousef Bozorgnia ◽  
Norman A. Abrahamson ◽  
Linda Al Atik ◽  
Timothy D. Ancheta ◽  
Gail M. Atkinson ◽  
...  
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Research Program ◽  
Epistemic Uncertainty ◽  
Response Spectra ◽  
Site Amplification ◽  
Earthquake Hazards ◽  
Research Project ◽  
Engineering Research ◽  
Crustal Earthquakes

The NGA-West2 project is a large multidisciplinary, multi-year research program on the Next Generation Attenuation (NGA) models for shallow crustal earthquakes in active tectonic regions. The research project has been coordinated by the Pacific Earthquake Engineering Research Center (PEER), with extensive technical interactions among many individuals and organizations. NGA-West2 addresses several key issues in ground-motion seismic hazard, including updating the NGA database for a magnitude range of 3.0–7.9; updating NGA ground-motion prediction equations (GMPEs) for the “average” horizontal component; scaling response spectra for damping values other than 5%; quantifying the effects of directivity and directionality for horizontal ground motion; resolving discrepancies between the NGA and the National Earthquake Hazards Reduction Program (NEHRP) site amplification factors; analysis of epistemic uncertainty for NGA GMPEs; and developing GMPEs for vertical ground motion. This paper presents an overview of the NGA-West2 research program and its subprojects.

Update of the Chiou and Youngs NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra

2014 ◽  
Vol 30 (3) ◽  
pp. 1117-1153 ◽  
Author(s):  
Brian S.-J. Chiou ◽  
Robert R. Youngs
Keyword(s):  
Ground Motion ◽  
Hanging Wall ◽  
Response Spectra ◽  
Rupture Directivity ◽  
Crustal Earthquakes ◽  
Aleatory Variability ◽  
Source Distance ◽  
Active Tectonic ◽  
Peak Ground Motion ◽  
Horizontal Ground Motion

We present an update to our 2008 NGA model for predicting horizontal ground motion amplitudes caused by shallow crustal earthquakes occurring in active tectonic environments. The update is based on analysis of the greatly expanded NGA-West2 ground motion database and numerical simulations. The updated model contains minor adjustments to our 2008 functional form related to style of faulting effects, hanging wall effects, scaling with the depth to top of rupture, scaling with sediment thickness, and the inclusion of additional terms for the effects of fault dip and rupture directivity. In addition, we incorporate regional differences in far-source distance attenuation and site effects between California and other active tectonic regions. Compared to our 2008 NGA model, the predicted medians by the updated model are similar for M > 7 and are lower for M < 5. The aleatory variability is larger than that obtained in our 2008 model.

Seismic Hazard Analysis for an NPP Site

2004 ◽  
Author(s):  
A. K. Ghosh ◽  
H. S. Kushwaha
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Hazard Analysis ◽  
Structural Response ◽  
Response Spectra ◽  
Seismic Fragility ◽  
Material Strength ◽  
Ground Acceleration ◽  
Hazard Response

The various uncertainties and randomness associated with the occurrence of earthquakes and the consequences of their effects on the NPP components and structures call for a probabilistic seismic risk assessment (PSRA). However, traditionally, the seismic design basis ground motion has been specified by normalised response spectral shapes and peak ground acceleration (PGA). The mean recurrence interval (MRI) used to be computed for PGA only. The present work develops uniform hazard response spectra i.e. spectra having the same MRI at all frequencies for Kakrapar Atomic Power Station site. Sensitivity of the results to the changes in various parameters has also been presented. These results determine the seismic hazard at the given site and the associated uncertainties. The paper also presents some results of the seismic fragility for an existing containment structure. The various parameters that could affect the seismic structural response include material strength of concrete, structural damping available within the structure and the normalized ground motion response spectral shape. Based on this limited case study the seismic fragility of the structure is developed. The results are presented as families of conditional probability curves plotted against the peak ground acceleration (PGA). The procedure adopted incorporates the various randomness and uncertainty associated with the parameters under consideration.

Relations between MaxRotD50 and Some Horizontal Components of Ground-Motion Intensity Used in Practice

2021 ◽  
Author(s):  
Alan Poulos ◽  
Eduardo Miranda
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Ground Motions ◽  
Geometric Mean ◽  
The Other ◽  
Horizontal Projection ◽  
Site Class ◽  
Engineering Research ◽  
Natural Logarithm ◽  
Horizontal Ground Motion

ABSTRACT The most commonly used intensity measure of ground motion in earthquake engineering is the 5% damped spectral ordinate, which varies in different directions. Several different measures have been proposed over the years to combine the intensity of the two horizontal recorded ground motions to derive ground-motion models as well as for design purposes. This study provides the relation to seven previously used measures of horizontal ground motion with respect to a recently proposed orientation-independent measure of horizontal ground-motion intensity referred to as MaxRotD50. This new measure of horizontal intensity is defined as the median value of the maximum spectral ordinate of two orthogonal directions computed for all possible nonredundant orientations. The relations are computed using 5065 pairs of horizontal ground motions taken from the database of ground motions recorded in shallow crustal earthquakes in active tectonic regions developed as part of the Pacific Earthquake Engineering Research Center’s Next Generation Attenuation-West2 project. Empirically derived period-dependent relations are presented for three quantities that permit transforming any of the seven other definitions of horizontal ground-motion intensity to MaxRotD50, namely, (1) geometric mean of the ratio of MaxRotD50 to any of the seven other measures of intensities, (2) standard deviation of the natural logarithm of the ratio of MaxRotD50 to any of the seven other measures of intensities, and (3) the correlation between the natural logarithm of the ratio of MaxRotD50 to the other measures of intensities and the natural logarithm of the other measure of intensity. In addition, the influence of site class at the recording station, earthquake magnitude, and distance to the horizontal projection of the rupture is examined on the geometric mean of the ratio of MaxRotD50 to the median intensity of all nonredundant orientations (i.e., RotD50), showing negligible influence of site class and only a relatively small influence of magnitude and distance.

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