Nonlinear Site Response Research Articles

Mapping of ground motion amplifications for the Fraser River delta in Greater Vancouver, Canada

The Fraser River delta in Greater Vancouver, Canada consists of deep soft deposits of silts and clays, and it is well known that the deep soil deposits can amplify the low frequency contents of ground motions. This study aims to investigate the effects of deep soil deposits in the delta on ground motion amplifications by using thorough site response simulations that account for the full soil profiles and a suite of recorded ground motions that covers a wide range of intensity levels. Based on both equivalent-linear and nonlinear site response simulations, the effects of soil depth (represented by natural period of the soil, TS) on ground motion amplifications for various spectral periods are clearly demonstrated. The ground motion amplification maps for various spectral periods and rock ground motion intensity levels are also generated to be used in the regional seismic hazard assessment for infrastructure. It is found that ground motions for long periods are substantially amplified in the center of the delta, while those for short periods are de-amplified when input rock motions are large.

Comprehensive amplification estimation of the Indo Gangetic Basin deep soil sites in the seismically active area

Site amplification coefficients and acceleration design response spectra (ADRS) for the deep Indo-Gangetic Basin (IGB) have been proposed. Non-linear site response analysis is carried out at 275 deep shear wave velocity (VS) profiles by selecting the input motion based on seismic hazard map for 10% probability of exceedence in 50 years. The spatial variation map of peak ground acceleration (PGA) and spectral acceleration (SA) at surface and various depths for the IGB are also presented. The bedrock PGA of 0.03–0.24 g increased to 0.1–0.97 g at surface and 0.05–0.35 g at a depth of 150 m. Maximum SA is observed between 0.08 s and 0.5 sec. The new site factors viz. Faand Fv are derived for newly defined spectral period range. Further, ADRS is constructed which depends on PGA and seismic site class as per NEHRP. Proposed ADRS is compared with different deep basin studies and BIS:1893.

Site response analysis and its comparison with the peruvian seismic design spectrum

The site response analyzes provide an idea of the behavior of the soil against strong ground motions, involving a large number of variables that determine the non-linear behavior of the soil. Due to the complexity of these analyzes, in practice the effects of nonlinear soil behavior are incorporated factors that modify the seismic response of a response spectrum in rock (linear behavior). In this study, nonlinear site response analysis has been performed for 50 soil profiles in an attempt for covering a wide range of shear wave velocity profiles using the software DEEPSOIL V.7. For this purpose, 06 seismic records have been spectrally adjusted to uniform hazard spectrum of 475, 1000 and 2475 years of return period. Subsequently, a comparison of the results obtained from the site response analysis with the parameters stipulated in the Peruvian Seismic Design Code E.030 (2018) was made, in order to determine the likelihood of these for the construction of design spectra. Discrepancies in the ranges of Vs values that this standard considers for the classification of soils and the factors that determine the width of the plate of the design spectrum have been found.

Site Response Analysis of Deep Sedimentary Deposits Using Electrical Resistivity Logging; Case Study: Guilan Province, Iran

Local geology of site and its properties can influence the input seismic wave specifications dramatically such as frequency content and duration while passing through soil stratums, making it inevitable to perform site-specific ground response analysis. For such analysis, soil’s dynamic properties including shear wave velocity (Vs) and shear modulus (G) are required, which are usually obtained using laboratory or field tests, commonly too expensive and time consuming for regions having deep sedimentary deposits. Electrical resistance of ground can be put into practice as a cost-effective alternative in assessing soils dynamic properties in order to be utilized in site response analysis, since the subsurface materials such as soil and rock have unique electrical properties. In this study, the feasibility of site response analysis using electrical logging has been evaluated using field data measurements of electrical resistivity and borehole logging through Guilan province, which is located on the southern shoreline of the Caspian Sea and in a region with high seismicity having deep sedimentary deposits. Nonlinear site response analysis as well as equivalent linear one is carried out in order to obtain the spectral response of the region, separately for the eight data points of the study. The acceleration time histories were synthesized using spectral matching technique integrating with probabilistic seismic hazard analysis. According to the results, the NL and EQL response and design spectrums, which are obtained in this study, show decent agreement with Iran’s 2800 seismic design spectrum, indicating acceptable performance of site response analysis using electrical resistivity logging.

Peak ground motions and characteristics of nonlinear site response during the 2018 Mw 6.6 Hokkaido eastern Iburi earthquake

The observed peak ground accelerations and peak ground velocities (PGVs) of the 2018 Mw 6.6 Hokkaido eastern Iburi earthquake generally followed the median values from ground motion prediction equations with reasonable errors at fault distances ≥ 50 km. However, at smaller distances, the equations significantly underestimated the peak ground motions, and it was eminent for PGVs. A comparison of surface-to-borehole spectral ratios of S-waves during the mainshock and other events revealed that the sites at smaller distances experienced various degrees of nonlinear site response. The two most widely known characteristics of nonlinear site response are the weakening of higher-frequency components and shifting of predominant frequencies to lower ones in comparison with the linear site response. At one of the sites that recorded the largest intensity of 7 in JMA scale of 0–7, the latter nonlinear effect was so dominant that the ground motions around the new predominant frequency got intensified by one order of magnitude in comparison with that during the weak-motions. Two sites, which were closely located, recorded vertical peak ground accelerations exceeding 1 g for the up-going motions. The recordings showed asymmetric waveforms and amplitudes characteristics of the nonlinear site response in extreme vertical ground motions recorded during a few earthquakes in the past. Few sites having lower vertical peak ground accelerations were also suspected of being experienced nonlinear site response on vertical motions. These findings suggest taking a cautious approach to enumerate the reduction in amplification at higher frequencies using the single-station horizontal-to-vertical (H-to-V) spectral ratio technique. However, we found that the H-to-V technique was still useful to detect nonlinearity. Finally, an ad hoc equation was derived to correct the nonlinear site amplification in predicting horizontal PGVs with respect to one of the most widely used attenuation models in Japan. The results indicated that the effect was much stronger for a larger input motion than that for a proportional change in the Vs30 values.

Notice of Retraction: Nonlinear Site Response at KiK‐net KMMH16 (Mashiki) and Heavily Damaged Sites during the 2016 Mw 7.1 Kumamoto Earthquake, Japan

Notice of Retraction: Nonlinear Site Response at KiK‐net KMMH16 (Mashiki) and Heavily Damaged Sites during the 2016 Mw 7.1 Kumamoto Earthquake, Japan

Delineation of subsurface profiles beneath the Kopili fault zone in northeast India utilizing coda portion

The Kopili fault (KF) zone, is witness to many seismic activities including the 1869 earthquake (7.8 MS), the 1943 earthquake (7.3 MS) and recent 2016 earthquake (6.7 MW) which occurred at certain time intervals. Considerable portion of KF zone and its neighbouring is characterized by alluvial soils which have higher potential of trapping seismic waves. This leads to intense amplification of ground shaking, necessitating a detailed study of subsurface profile beneath KF. The H/V Spectral Ratio of strong-motion recordings is an effective tool to evaluate such nonlinear site responses, and to develop a subsurface velocity profile is an important step toward hazard mitigation. In this work, we used 14 seismic stations, nearby this fault to construct the subsurface profile. This study suggests that H/V ratios obtained from coda portion of seismogram are almost independent of the coda window length. We applied diffuse field concept to produce an inverted S-wave as well as P-wave velocity profile. The inverted profiles show significant correlation with the underlying site class as well as exhibit an excellent match with already reported attenuation quality factors for this region. For few selected sites, inferred velocity estimates become 500 m/s at a depth of 25 m or shallower. Interestingly, it is observed that two nearby receiving sites are characterized by different shear wave velocity profiles at shallower depths. However, in deeper depths, they are found to converge. All results are comprehensively analyzed and their implications are accordingly outlined.

High frequency content in nonlinear soil response: A numerical artifact or a reality?

This article probes the reasons for the presence of high frequency components, which are not a part of the input, in the output of nonlinear site response analysis. The nonlinear site response analysis of a single soil element, under a single frequency sinusoidal displacement, is conducted to demonstrate the presence of frequencies higher than the input frequency in the soil element's shear stress and the free surface acceleration. The parameters of this one element problem are chosen carefully to minimize numerical errors. The shape of the stress-strain hysteresis loop is found to be the main cause for the presence of these higher frequencies. A quasi-static problem similar to the direct shear test is then considered to analyze the effect of different hysteresis shapes. Through this analysis, it is numerically and analytically shown that any deviation of the stress-strain hysteresis shape from a perfect ellipse results in output frequencies higher than the input frequency and the number of higher frequencies produced depends on whether the hysteresis shape is smooth or pointed.

One Dimensional Site Response Analysis of Liquefaction Potential along Coastal Area of Bengkulu City, Indonesia

This paper presents one dimensional non-linear site response analysis of liquefaction potential caused by the 2000 and the 2007 earthquakes in coastal area of Bengkulu City, Bengkulu, Indonesia. Site investigations, including Standard Penetration Test (SPT) and shear wave velocity (VS) measurement, were conducted in three locations along the coastal area of Bengkulu City. Further, the site investigation data were used in simulation of one-dimensional non-linear site response analysis by applying the synthetic ground motions at bedrock. The results show that liquefaction could happen at 0 to 1.5 m deep. This was indicated by the excess pore water pressure ratio (ru) which exceeded one. At depth between 1.5 m and 20 m, the excess pore water pressure almost reached the initial effective stress decreasing the effective confinement pressure close to zero. The results also indicated that liquefaction is possible to occur in this depth range if a stronger earthquake occurs.

Reply to Discussion of “Effect of Site Conditions on Site Amplification Factors and Seismic Design Spectra for Bridges” by Alireza Eskandarinejad

Site amplification factors and seismic design spectra for bridges are affected by site conditions. Influence of the following parameters on site amplification factors, Fa and Fv, is investigated herein: (1) confining pressure used in Modulus and Reduction Damping (MRD) curves, (2) shear wave velocity (Vs) of seismic input motions and (3) necessity of using nonlinear site response analysis. It was concluded that the mentioned parameters had an insignificant impact on Fa and Fv values in majority of the analysis cases and had a low to moderate impact for a small number of analysis cases in few site classes only when subjected to a limited set of ground motions.

Non-linear Site Response Analysis of Soil Sites in Northern Thailand during the Mw 6.8 Tarlay Earthquake

Non-linear Site Response Analysis of Soil Sites in Northern Thailand during the Mw 6.8 Tarlay Earthquake

A simplified model to estimate non-liquefiable NEHRP F site design spectra

The International Building Code requires a site-specific investigation for NEHRP F sites. However, established procedures for performing site-specific investigations of NEHRP F sites are limited. This study developed a simplified model to estimate design spectra for non-liquefiable NEHRP F sites to provide guidance for these cases. The model is based on the results of 4695 one-dimensional effective stress nonlinear site response analyses. It is intended to be used jointly with site-specific response analyses. The model is dependent on the period, design ground motion intensity, and site properties, and it characterizes the uncertainty of the estimate. The sensitivity of the results to reasonable variations in input parameters is investigated. The model is validated against field observations and compared with 80% NEHRP E site design spectra. The simplified model can capture the trends and magnitude of acceleration response spectra calculated from the site response analyses for all ground motions tested. Design spectra may fall below the 80% NEHRP E site design spectra for moderate to large levels of shaking intensity due to soil nonlinearity.

Temporal Nonlinear Site Response During Kumamoto Mw 7.0 Earthquake Inferred from Borehole Strong Motion Data

The Mw 7.0 Kumamoto earthquake (Japan) occurred on 15 April 2016 – 16:25 UTC. Using both borehole and surface ground accelerations recorded by Japanese strong motion network KiK-net, we investigate temporal changes of nonlinear site response in the shallow crust associated with Kumamoto earthquake. We compute the spectral ratios of windowed records from a pair of surface and borehole stations, and then use the sliding-window spectral ratios to track the temporal changes in the site response of various sites at different levels of peak ground acceleration(PGA). At the site OITH11 where two distinct groups of wave trains are recorded, the resonant frequency briefly recovers in between, and then followed by an apparent logarithmic recovery. We investigate the percentage drop of peak frequency and peak spectral ratio during the main shock at different PGA levels. Our results show clear drops of resonant frequency and peak spectra ratio of ~10–40% during the main shock, and the drops generally increase with the PGA level.

Verification of the Ramberg-Osgood Material Model in Midas GTS NX with the Modeling of Torsional Simple Shear Tests

This study focuses on the back analysis of a geotechnical laboratory test with nonlinear finite element modeling using the Ramberg-Osgood material model. This model has been used by several authors recently for nonlinear ground response analysis and it has been implemented by Midas into their commercial finite element code Midas GTS NX 2014. The verification of the model for 1D nonlinear site response analysis can be found in the documentation of the software package. In this study, Torsional Simple Shear tests were modeled and a comprehensive study was performed to provide verification of the material model for static torsional loading and axisymmetric conditions.

Linear and nonlinear site response analyses to determine dynamic soil properties of Kirikkale

In order to make reliable earthquake-resistant design of civil engineering structures, one of the most important considerations in a region with high seismicity is to pay attention to the local soil condition of regions. It is aimed in the current study at specifying dynamic soil characteristics of Kirikkale city center conducting the 1-D equivalent linear and non-linear site response analyses. Due to high vulnerability and seismicity of the city center of Kirikkale surrounded by active many faults, such as the North Anatolian Fault (NAF), the city of Kirikkale is classified as highly earthquake-prone city. The first effort to determine critical site response parameter is to perform the seismic hazard analyses of the region through the earthquake record catalogues. The moment magnitude of the city center is obtained as Mw=7.0 according to the recorded probability of exceedance of 10% in the last 50 years. Using the data from site tests, the 1-D equivalent linear (EL) and nonlinear site response analyses (NL) are performed with respect to the shear modulus reduction and damping ratio models proposed in literature. The important engineering parameters of the amplification ratio, predominant site period, peak ground acceleration (PGA) and spectral acceleration values are predicted. Except for the periods between the period of T=0.2-1.0 s, the results from the NL are obtained to be similar to the EL results. Lower spectral acceleration values are estimated in the locations of the city where the higher amplification ratio is attained or vice-versa. Construction of high-rise buildings with modal periods higher than T=1.0 s are obtained to be suitable for the city of Kirikkale. The buildings at the city center are recommended to be assessed with street survey rapid structural evaluation methods so as to mitigate seismic damages. The obtained contour maps in this study are estimated to be effective for visually characterizing the city in terms of the considered parameters.

Developing a model for the prediction of ground motions due to earthquakes in the Groningen gas field

AbstractMajor efforts are being undertaken to quantify seismic hazard and risk due to production-induced earthquakes in the Groningen gas field as the basis for rational decision-making about mitigation measures. An essential element is a model to estimate surface ground motions expected at any location for each earthquake originating within the gas reservoir. Taking advantage of the excellent geological and geophysical characterisation of the field and a growing database of ground-motion recordings, models have been developed for predicting response spectral accelerations, peak ground velocity and ground-motion durations for a wide range of magnitudes. The models reflect the unique source and travel path characteristics of the Groningen earthquakes, and account for the inevitable uncertainty in extrapolating from the small observed magnitudes to potential larger events. The predictions of ground-motion amplitudes include the effects of nonlinear site response of the relatively soft near-surface deposits throughout the field.

Near-source effects and non-linear site response at Kashiwazaki-Kariwa Nuclear Power Plant, in the 2007 Chuetsu-Oki earthquake: evidence from surface and downhole records and 1D numerical simulations

The aim of this paper is to clarify the extent of near-source effects and non-linear soil response that took place at the Japanese nuclear site of Kashiwazaki-Kariwa, during the MW 6.6 Niigata-Ken Chūetsu-Oki earthquake (July, 16th 2007). The interest of this case study stems from the relative small source-to-site distance and shallow hypocenter depth, coupled with the consistent seismic record database available from two down-hole arrays of strong motion accelerometers, installed within the nuclear site. Records were processed first to highlight those features related to near-source conditions, such as directivity and polarization, and, subsequently, to identify dependence of site response on the direction of motion and on the non-linear soil behaviour. Moreover, borehole interferometry was used to check the two available velocity profiles (estimated by in situ PS logging) used for 1D linear equivalent numerical simulations. In one case, an improved agreement with the empirical amplification functions was obtained using a smoothed profile. The main non-linear features highlighted by signal processing were globally reproduced by means of linear-equivalent analyses, that pointed out the strong influence of the input motion direction. Among the principal results of this research, it was found that the hanging-wall and directivity effects along with the non-linear site-effects dominate the ground response during the main shock, and that the site amplification features are strongly dependent on the rotation angle of the horizontal components.

Amplification of Strong Ground Motions at Heathcote Valley during the 2010–2011 Canterbury Earthquakes: The Role of 2D Nonlinear Site Response

Research Article| September 25, 2017 Amplification of Strong Ground Motions at Heathcote Valley during the 2010–2011 Canterbury Earthquakes: The Role of 2D Nonlinear Site Response Seokho Jeong; Seokho Jeong aQuakeCoRE, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand, seokho.jeong@canterbury.ac.nz Search for other works by this author on: GSW Google Scholar Brendon A. Bradley Brendon A. Bradley bDepartment of Civil and Natural Resources Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand, brendon.bradley@canterbury.ac.nzcCurrently at Department of Civil and Environmental Engineering, Stanford University, Stanford, California. Search for other works by this author on: GSW Google Scholar Author and Article Information Seokho Jeong aQuakeCoRE, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand, seokho.jeong@canterbury.ac.nz Brendon A. Bradley bDepartment of Civil and Natural Resources Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand, brendon.bradley@canterbury.ac.nzcCurrently at Department of Civil and Environmental Engineering, Stanford University, Stanford, California. Publisher: Seismological Society of America First Online: 27 Sep 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 Bulletin of the Seismological Society of America (2017) 107 (5): 2117–2130. https://doi.org/10.1785/0120160389 Article history First Online: 27 Sep 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Seokho Jeong, Brendon A. Bradley; Amplification of Strong Ground Motions at Heathcote Valley during the 2010–2011 Canterbury Earthquakes: The Role of 2D Nonlinear Site Response. Bulletin of the Seismological Society of America 2017;; 107 (5): 2117–2130. doi: https://doi.org/10.1785/0120160389 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract This article presents a quantitative case study on the site amplification effect observed at Heathcote Valley, New Zealand, during the 2010–2011 Canterbury earthquake sequence for 10 events that produced notable ground acceleration amplitudes up to 1.4g and 2.2g in the horizontal and vertical directions, respectively. We performed finite‐element analyses of the dynamic response of the valley, accounting for the realistic basin geometry and the soil nonlinear response. The site‐specific simulations performed significantly better than both empirical ground‐motion models and physics‐based regional‐scale ground‐motion simulations (which empirically account for the site effects), reducing the spectral acceleration prediction bias by a factor of 2 in short vibration periods. However, our validation exercise demonstrated that it was necessary to quantify the level of uncertainty in the estimated bedrock motion using multiple recorded events to understand how much the simplistic model can overestimate or underestimate the ground‐motion intensities. Inferences from the analyses suggest that the Rayleigh waves generated near the basin edge contributed significantly to the observed high‐frequency (⁠f>3 Hz⁠) amplification, in addition to the amplification caused by the strong soil–rock impedance contrast at the site fundamental frequency. Models with and without considering soil nonlinear response illustrate, as expected, that the linear‐elastic assumption severely overestimates ground motions in high frequencies for strong earthquakes, especially when the contribution of basin‐edge‐generated Rayleigh waves becomes significant. Our analyses also demonstrate that the effect of pressure‐dependent soil velocities on the high‐frequency ground motions is as significant as the amplification caused by the basin‐edge‐generated Rayleigh waves. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

VS30, slope, H800 and f0: performance of various site-condition proxies in reducing ground-motion aleatory variability and predicting nonlinear site response

The aim of this paper is to investigate the ability of various site-condition proxies (SCPs) to reduce ground-motion aleatory variability and evaluate how SCPs capture nonlinearity site effects. The SCPs used here are time-averaged shear-wave velocity in the top 30 m (VS30), the topographical slope (slope), the fundamental resonance frequency (f0) and the depth beyond which Vs exceeds 800 m/s (H800). We considered first the performance of each SCP taken alone and then the combined performance of the 6 SCP pairs [VS30–f0], [VS30–H800], [f0–slope], [H800–slope], [VS30–slope] and [f0–H800]. This analysis is performed using a neural network approach including a random effect applied on a KiK-net subset for derivation of ground-motion prediction equations setting the relationship between various ground-motion parameters such as peak ground acceleration, peak ground velocity and pseudo-spectral acceleration PSA (T), and Mw, RJB, focal depth and SCPs. While the choice of SCP is found to have almost no impact on the median ground-motion prediction, it does impact the level of aleatory uncertainty. VS30 is found to perform the best of single proxies at short periods (T < 0.6 s), while f0 and H800 perform better at longer periods; considering SCP pairs leads to significant improvements, with particular emphasis on [VS30–H800] and [f0–slope] pairs. The results also indicate significant nonlinearity on the site terms for soft sites and that the most relevant loading parameter for characterising nonlinear site response is the “stiff” spectral ordinate at the considered period.Graphical .

Modelling the non-linear site response at the LSST down-hole accelerometer array in Lotung

Down-hole array observations are extremely useful to investigate site amplification effects and to validate numerical modelling techniques for site response. In this paper the ground response of the Lotung experiment site (Taiwan), measured along a down-hole accelerometer array during a weak and a strong motion event, is simulated using different numerical techniques of increasing level of complexity: 1) a simple equivalent-linear visco-elastic procedure, 2) a total stress time-domain scheme using a pressure-dependent hyperbolic model and 3) a fully-coupled approach implementing an advanced elasto-plastic soil model. The numerical models are calibrated against resonant column data and in-situ cross-hole measurements. The two horizontal components of the input motion are applied separately at bedrock level. The results of the simple and advanced numerical simulations are compared with the down-hole motions recorded in-situ during the investigated seismic events in terms of acceleration time histories and response spectra. The comparison between in-situ measurements and predicted results highlights the well-known limitations of the frequency-domain technique. It also shows some improved predictive capabilities of the total stress time-domain scheme and demonstrates the excellent performance of the fully-coupled advanced non-linear approach.