Prediction of Soil Effects on Seismic Motions: A Comparative Case Study

1997 ◽  
Vol 13 (3) ◽  
pp. 333-361 ◽  
Author(s):  
George D. Bouckovalas
Keyword(s):  
Response Spectra ◽  
Comparative Case Study ◽  
Seismic Excitations ◽  
Ground Acceleration ◽  
Ground Shaking ◽  
Intermediate Period ◽  
Opposite Case ◽  
Site Characteristics ◽  
Average Shear ◽  
Soil Effects

Empirical predictions of soil effects on seismic ground shaking are related to 1-D seismic response analyses. The comparison focuses upon the peak ground acceleration ( amax) and velocity ( Vmax), the elastic acceleration response spectra (Sa) and the average horizontal Fourier amplitudes over a short and an intermediate period band (AHFA, AHFA*). Empirical predictions in terms of site geology are within the overall range of analytical predictions for amax and Vmax, but they do not depict the detailed effects of seismic motion and site characteristics. In addition, they agree to analytical predictions of Sa for relatively deep and flexible sites, but differ significantly for other sites. Empirical predictions in terms of the average shear wave velocity, agree well with analytical predictions for amax, Vmax, AHFA and AHFA* in the case of shallow and stiff sites subjected to weak seismic excitations, but they are relatively higher in the opposite case. Empirical predictions of Sa are generally within the range of analytical predictions, although empirically predicted peak amplification can not be related to resonance between the soil and the superstructure.

Updated PGA, PGV, and Spectral Acceleration Attenuation Relations for Iran

2012 ◽  
Vol 28 (1) ◽  
pp. 257-276 ◽  
Author(s):  
Hamid Saffari ◽  
Yasuko Kuwata ◽  
Shiro Takada ◽  
Abbas Mahdavian
Keyword(s):  
Response Spectra ◽  
Peak Ground Velocity ◽  
Model Parameters ◽  
Ground Acceleration ◽  
Attenuation Relations ◽  
Data Set ◽  
Site Class ◽  
Source Regions ◽  
Average Shear ◽  
Fault Mechanism

We have developed updated attenuation relations for peak ground acceleration (PGA), peak ground velocity (PGV), and acceleration response spectra with 5% damping on the basis of the data (78 earthquakes and 351 records) pertaining to strong ground motion in Iran. Moment magnitude, distance, fault mechanism, site class, and zone were the model parameters considered. A term for the saturation of the acceleration amplitude was also used in the model in order to improve the estimations in near-source regions. A nonlinear regression analysis was performed to obtain the coefficients. A comparison between the data set used in the current study for Iran and two next generation attenuation (NGA) models showed good correlation between our model and the Campbell-Bozorgnia NGA model. The model described is applicable for moment magnitudes from 5.0 to 7.3, distances from 15 to 135 km, and site classes with an average shear-wave velocity at a subsurface depth of 30 m (AVS30) of more than 175 m/s.

The Seismic Microzonation of the City of Catania (Italy) for the Etna Scenario Earthquake (M = 6.2) of 20 February 1818

2012 ◽  
Vol 28 (2) ◽  
pp. 573-594 ◽  
Author(s):  
Salvatore Grasso ◽  
Michele Maugeri
Keyword(s):  
Nonlinear Models ◽  
Seismic Hazard Assessment ◽  
Response Spectra ◽  
Response Analysis ◽  
Ground Response Analysis ◽  
Ground Acceleration ◽  
Ground Shaking ◽  
Earthquake Scenario ◽  
Lower Magnitude ◽  
The City

Based on the seismic history of the city of Catania (Italy), the Etna earthquake of 20 February 1818 ( IMCS = VIII–IX, MS = 6.2) has been considered as an earthquake scenario. Despite its lower magnitude, the Etna 1818 earthquake can be accounted for in the seismic hazard assessment of Catania, since it may cause heavy damage to the city. The epicenter was located along the southeastern flanks of the Etna Volcano, close to the municipal area of the city of Catania. The ground-response analysis at the surface has been obtained by one-dimensional (1-D) nonlinear models. According to the response spectra obtained through the application of the nonlinear models, the city of Catania has been divided into zones with different peak ground acceleration at the surface. A ground-shaking map for the urban area of the city of Catania was generated via GIS for the 1818 earthquake scenario.

Response Spectra at Liquefaction Sites during Shallow Crustal Earthquakes

2015 ◽  
Vol 31 (4) ◽  
pp. 2325-2349 ◽  
Author(s):  
James R. Gingery ◽  
Ahmed Elgamal ◽  
Jonathan D. Bray
Keyword(s):  
Response Spectra ◽  
Site Amplification ◽  
Soil Liquefaction ◽  
Positive Bias ◽  
Acceleration Response ◽  
Ground Acceleration ◽  
Ground Shaking ◽  
Crustal Earthquakes ◽  
Proposed Model ◽  
A Site

Site amplification studies and building code provisions recognize that soil liquefaction can alter the characteristics of ground shaking at a site. However, guidance as to how the amplitudes of spectral accelerations are modified is lacking. In this paper, available recorded ground motions from shallow crustal earthquakes at sites that exhibited evidence of liquefaction are investigated. Analysis of residuals computed relative to Next Generation Attenuation (NGA) estimates reveal positive bias at longer periods, slight negative bias at intermediate periods, and slight positive bias at short periods. Trends with V S30, NGA-estimated peak ground acceleration (PGA), and moment magnitude are also observed. A model is developed that removes the initially observed residual bias and reduces uncertainty. The proposed model can be used to adjust NGA-estimated acceleration response spectra to account for the effects of liquefaction on ground shaking.

Evaluation of floor acceleration demands from the 2017 Mexico City code seismic provisions using a continuous elastic model and records of instrumented buildings

2020 ◽  
Vol 36 (2_suppl) ◽  
pp. 213-237
Author(s):  
Miguel A Jaimes ◽  
Adrián D García-Soto
Keyword(s):  
Mexico City ◽  
Seismic Design ◽  
Soft Soil ◽  
Response Spectra ◽  
Elastic Model ◽  
Ground Acceleration ◽  
Nonstructural Components ◽  
Floor Response Spectra ◽  
Instrumented Buildings ◽  
Floor Acceleration

This study presents an evaluation of floor acceleration demands for the design of rigid and flexible acceleration-sensitive nonstructural components in buildings, calculated using the most recent Mexico City seismic design provisions, released in 2017. This evaluation includes two approaches: (1) a simplified continuous elastic model and (2) using recordings from 10 instrumented buildings located in Mexico City. The study found that peak floor elastic acceleration demands imposed on rigid nonstructural components into buildings situated in Mexico City might reach values of 4.8 and 6.4 times the peak ground acceleration at rock and soft sites, respectively. The peak elastic acceleration demands imposed on flexible nonstructural components in all floors, estimated using floor response spectra, might be four times larger than the maximum acceleration of the floor at the point of support of the component for buildings located in rock and soft soil. Comparison of results from the two approaches with the current seismic design provisions revealed that the peak acceleration demands and floor response spectra computed with the current 2017 Mexico City seismic design provisions are, in general, adequate.

scholarly journals Case Study of a Heavily Damaged Building during the 2016 MW 7.8 Ecuador Earthquake: Directionality Effects in Seismic Actions and Damage Assessment

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 74
Author(s):  
Luis A. Pinzón ◽  
Luis G. Pujades ◽  
Irving Medranda ◽  
Rodrigo E. Alva
Keyword(s):  
Damage Assessment ◽  
Strong Motion ◽  
Response Spectra ◽  
Seismic Action ◽  
Damage State ◽  
Ground Acceleration ◽  
Intensity Measures ◽  
Capacity Curves ◽  
Building Orientation

In this work, the directionality effects during the MW 7.8 earthquake, which occurred in Muisne (Ecuador) on 16 April 2016, were analyzed under two perspectives. The first one deals with the influence of these effects on seismic intensity measures (IMs), while the second refers to the assessment of the expected damage of a specific building located in Manta city, Ecuador, as a function of its azimuthal orientation. The records of strong motion in 21 accelerometric stations were used to analyze directionality in seismic actions. At the closest station to the epicenter (RRup = 20 km), the peak ground acceleration was 1380 cm/s2 (EW component of the APED station). A detailed study of the response spectra ratifies the importance of directionality and confirms the need to consider these effects in seismic hazard studies. Differences between IMs values that consider the directionality and those obtained from the as-recorded accelerograms are significant and they agree with studies carried out in other regions. Concerning the variation of the expected damage with respect to the building orientation, a reinforced concrete building, which was seriously affected by the earthquake, was taken as a case study. For this analysis, the accelerograms recorded at a nearby station and detailed structural documentation were used. The ETABS software was used for the structural analysis. Modal and pushover analyses were performed, obtaining capacity curves and capacity spectra in the two main axes of the building. Two advanced methods for damage assessment were used to obtain fragility and mean damage state curves. The performance points were obtained through the linear equivalent approximation. This allows estimation and analysis of the expected mean damage state and the probability of complete damage as functions of the building orientation. Results show that the actual probability of complete damage is close to 60%. This fact is mainly due to the greater severity of the seismic action in one of the two main axes of the building. The results are in accordance with the damage produced by the earthquake in the building and confirm the need to consider the directionality effects in damage and seismic risk assessments.

Spatial Seismic Excitations and Response Spectra

1993 ◽  
Vol 119 (12) ◽  
pp. 2449-2460 ◽  
Author(s):  
Zbigniew Zembaty ◽  
Steen Krenk
Keyword(s):  
Response Spectra ◽  
Seismic Excitations

Source dynamics of the 1979 Imperial Valley earthquake from near-source observations (of ground acceleration and velocity)

1982 ◽  
Vol 72 (6A) ◽  
pp. 1957-1968
Author(s):  
Mansour Niazi
Keyword(s):  
Particle Acceleration ◽  
Particle Velocity ◽  
High Frequency ◽  
Observation Point ◽  
P Wave ◽  
Imperial Valley ◽  
Ground Acceleration ◽  
Data Set ◽  
Ground Shaking ◽  
Fault Surface

abstract Two sets of observations obtained during the 15 October 1979 Imperial Valley earthquake, MS 6.9, are presented. The data suggest different dynamic characteristics of the source when viewed in different frequency bands. The first data set consists of the observed residuals of the horizontal peak ground accelerations and particle velocity from predicted values within 50 km of the fault surface. The residuals are calculated from a nonlinear regression analysis of the data (Campbell, 1981) to the following empirical relationships, PGA = A 1 ( R + C 1 ) − d 1 , PGV = A 2 ( R + C 2 ) − d 2 in which R is the closest distance to the plane of rupture. The so-calculated residuals are correlated with a positive scalar factor signifying the focusing potential at each observation point. The focusing potential is determined on the basis of the geometrical relation of the station relative to the rupture front on the fault plane. The second data set consists of the acceleration directions derived from the windowed-time histories of the horizontal ground acceleration across the El Centro Differential Array (ECDA). The horizontal peak velocity residuals and the low-pass particle acceleration directions across ECDA require the fault rupture to propagate northwestward. The horizontal peak ground acceleration residuals and the high-frequency particle acceleration directions, however, are either inconclusive or suggest an opposite direction for rupture propagation. The inconsistency can best be explained to have resulted from the incoherence of the high-frequency radiation which contributes most effectively to the registration of PGA. A test for the sensitivity of the correlation procedure to the souce location is conducted by ascribing the observed strong ground shaking to a single asperity located 12 km northwest of the hypocenter. The resulting inconsistency between the peak acceleration and velocity observations in relation to the focusing potential is accentuated. The particle velocity of Delta Station, Mexico, in either case appears abnormally high and disagrees with other observations near the southeastern end of the fault trace. From the observation of a nearly continuous counterclockwise rotation of the plane of P-wave particle motion at ECDA, the average rupture velocity during the first several seconds of source activation is estimated to be 2.0 to 3.0 km/sec. A 3 km upper bound estimate of barrier dimensions is tentatively made on the basis of the observed quasiperiodic variation of the polarization angles.

scholarly journals Probabilistic seismic hazard analysis using the logic tree approach – Patna district (India)

2019 ◽  
Vol 19 (10) ◽  
pp. 2097-2115 ◽  
Author(s):  
Panjamani Anbazhagan ◽  
Ketan Bajaj ◽  
Karanpreet Matharu ◽  
Sayed S. R. Moustafa ◽  
Nassir S. N. Al-Arifi
Keyword(s):  
Epistemic Uncertainty ◽  
Hazard Analysis ◽  
Response Spectra ◽  
Maximum Magnitude ◽  
Logic Tree ◽  
Ground Acceleration ◽  
Incremental Method ◽  
Seismicity Parameters ◽  
Hazard Response ◽  
Tree Approach

Abstract. Peak ground acceleration (PGA) and study area (SA) distribution for the Patna district are presented considering both the classical and zoneless approaches through a logic tree framework to capture the epistemic uncertainty. Seismicity parameters are calculated by considering completed and mixed earthquake data. Maximum magnitude is calculated using three methods, namely the incremental method, Kijko method, and regional rupture characteristics approach. The best suitable ground motion prediction equations (GMPEs) are selected by carrying out an “efficacy test” using log likelihood. Uniform hazard response spectra have been compared with Indian standard BIS 1893. PGA varies from 0.38 to 0.30 g from the southern to northern periphery considering 2 % probability of exceedance in 50 years.

scholarly journals Earthquakes on the surface: earthquake location and area based on more than 14 500 ShakeMaps

2018 ◽  
Vol 18 (6) ◽  
pp. 1665-1679
Author(s):  
Stephanie Lackner
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Earthquake Location ◽  
Primary Concern ◽  
Ground Acceleration ◽  
Ground Shaking ◽  
Geographic Context ◽  
The Social ◽  
Strong Ground

Abstract. Earthquake impact is an inherently interdisciplinary topic that receives attention from many disciplines. The natural hazard of strong ground motion is the reason why earthquakes are of interest to more than just seismologists. However, earthquake shaking data often receive too little attention by the general public and impact research in the social sciences. The vocabulary used to discuss earthquakes has mostly evolved within and for the discipline of seismology. Discussions on earthquakes outside of seismology thus often use suboptimal concepts that are not of primary concern. This study provides new theoretic concepts as well as novel quantitative data analysis based on shaking data. A dataset of relevant global earthquake ground shaking from 1960 to 2016 based on USGS ShakeMap data has been constructed and applied to the determination of past ground shaking worldwide. Two new definitions of earthquake location (the shaking center and the shaking centroid) based on ground motion parameters are introduced and compared to the epicenter. These definitions are intended to facilitate a translation of the concept of earthquake location from a seismology context to a geographic context. Furthermore, the first global quantitative analysis on the size of the area that is on average exposed to strong ground motion – measured by peak ground acceleration (PGA) – is provided.

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 />

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