Seismic Ground Response Analysis of Some Typical Sites of Guwahati City

2013 ◽  
Vol 4 (1) ◽  
pp. 83-101 ◽  
Author(s):  
Shiv Shankar Kumar ◽  
A. Murali Krishna
Keyword(s):  
Ground Motion ◽  
Amplitude Ratio ◽  
Response Spectrum ◽  
Strong Motion ◽  
Response Analysis ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Ground Acceleration ◽  
Surface Level ◽  
Guwahati City

In this study, one dimensional equivalent–linear ground response analyses were performed for some typical sites in the Guwahati city, India. Six bore locations covering about 250 km2 area of the city were considered for the analyses. As the strong motion significantly influences the ground response, seven different recorded ground motions, varying in magnitude (6.1 to 8.1) and other ground motion parameters, were adopted. Seismic site analyses were carried out for all layers of borelogs using all the seven earthquakes. Results are presented in terms of surface acceleration histories, strain and shear stress ratio variation, response spectrum, Fourier amplitude ratio versus frequency. The results indicate that accelerations were amplified the most at the surface level. The range of peak ground acceleration (PGA) values obtained at the ground surface is about 0.2 g to 0.79 for a range of PGA considered at bedrock level (rigid half space at bottom of borelog) of 0.1 g to 0.34 g. The Fourier amplifications of ground motion at surface are in the range of 4.14 – 8.99 for a frequency band of 1.75 Hz to 3.13 Hz. The maximum spectral acceleration at six locations varies in the range of 1.0 g – 4.71 g for all the seven earthquakes. The study clearly demonstrated the role for site effect and the type of ground motion on the ground response. For a given earthquake motion, amplification factors at surface level change by almost about 20% to 70% depending on local site conditions.

Study on the Comparison of Ground Response Analysis for Class І Site

2014 ◽  
Vol 919-921 ◽  
pp. 1031-1034
Author(s):  
Xiao Fei Li ◽  
Rui Sun
Keyword(s):  
Strong Motion ◽  
Response Spectra ◽  
Response Analysis ◽  
Acceleration Response ◽  
Seismic Response Analysis ◽  
Ground Response ◽  
Real Situation ◽  
Ground Response Analysis ◽  
Ground Acceleration ◽  
Maximum Shear Strain

In order to test the applicable of the two equivalent linear seismic response analysis procedures SHAKE2000 and LSSRLI-1 for class І site, 21 underground strong motion records were selected from 11 stations of KiK-net as input earthquake motions. By using these two programs to calculate the peak ground acceleration, soil maximum shear strain and acceleration response spectra. By comparing the results of the two procedures and the measured results to evaluate the proximity of these two methods and then judge which program is closer to the real situation. Studies have shown that in class І site, the results of SHAKE2000 and LSSRLI-1 differ little; but according to the measured records, there are some differences between the two programs results and the measured records. While no matter comparing from which side, SHAKE2000 is closer to the earthquake records.

Challenges in the definition of input motions for forensic ground-response analysis in the near-source region

2021 ◽  
pp. 875529302110013
Author(s):  
Nikolaos Ntritsos ◽  
Misko Cubrinovski ◽  
Brendon A Bradley
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Source Region ◽  
Strong Motion ◽  
Target Site ◽  
Response Analysis ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Recording Station

This article scrutinizes the determination of input motions for forensic ground-response analysis in the near-source region, based on recorded surface ground motions at strong-motion station sites, from the same event. The first part of the article draws upon observed ground motions from the 22 February 2011 6.2 Mw Christchurch earthquake to discuss key challenges of the problem associated with the strong spatial variation of ground motion in the near-source region. Effects from the complexity of the rupture, propagation of seismic waves through complex geological structures, and site characteristics are explored. It is argued that, because of the strongly varying source-path “signature” on near-source ground motions, “reference” input motions for ground-response analysis must be specific to, and have similar signature characteristics (be “compatible”) with, the target site which is subject to the analysis. The second part of the article presents a four-step procedure for the derivation of site-specific input motions involving (1) determination of the reference layer where the input motion is to be applied in the analysis, (2) record selection considering the appropriateness of the recording station site for deconvolution and its compatibility with the target site, (3) deconvolution of the selected record to remove local site effects from the recorded ground motion, and (4) scaling of the deconvolved motion to account for differences in the source-to-site distance between the recording station and the target site. As part of the proposed procedure, a novel (amplitude-duration) scaling method is presented. Results from one-dimensional (1D) effective-stress analysis of two target Christchurch sites using input motions from the proposed procedure are used to critically evaluate the procedure and discuss essential requirements for its successful application.

Study on the Ground Response Analysis for Stiff Soil

2014 ◽  
Vol 915-916 ◽  
pp. 122-125
Author(s):  
Xiao Fei Li ◽  
Rui Sun ◽  
Xiao Bo Yu
Keyword(s):  
Seismic Response ◽  
Working Conditions ◽  
Strong Motion ◽  
Response Spectra ◽  
Response Analysis ◽  
Seismic Response Analysis ◽  
Ground Response Analysis ◽  
Ground Acceleration ◽  
Strong Motion Records ◽  
Stiff Soil

In order to test the applicable of the seismic response analysis procedures SHAKE2000 and LSSRLI-1 for class ІІ site, 17 stations and 35 underground strong motion records of KiK-net are selected from Class ІІ site. 210 working conditions are used to verify the applicability of the two soil seismic response analysis programs at Class ІІ site. These two programs are used to calculate the selected working conditions, giving the peak acceleration of the ground, the shear strain and the ground acceleration response spectra. By analyzing the results of the two programs and the measured results to assess the degree of difference between the two methods and which program is closer to the real situation. Studies have shown that in class ІІ site, in most cases, the results of SHAKE2000 and LSSRLI-1 differ little. While comparing with the actual records, SHAKE2000 is closer to the strong motion records.

scholarly journals Stochastic Nonlinear Ground Response Analysis Considering Existing Boreholes Locations by the Geostatistical Method

2021 ◽  
Author(s):  
A.H. Amjadi ◽  
Ali johari
Keyword(s):  
Random Field ◽  
Mean Value ◽  
Response Analysis ◽  
Soil Parameters ◽  
Seismic Responses ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Ground Acceleration ◽  
Geostatistical Method ◽  
Stationary Random Field

Abstract The field and laboratory evidence of nonlinear soil behavior, even at small strains, emphasizes the ‎importance of employing nonlinear methods in seismic ground response analysis. Additionally, ‎determination of dynamic characteristics of soil layers always includes some degree of uncertainty. Most of ‎previous stochastic studies of ground response analysis have focused only on uncertainties of soil ‎parameters, and the effect of soil sample location has been mostly ignored. This study attempts to couple ‎nonlinear time-domain ground response analysis with uncertainty of soil parameters considering existing ‎boreholes’ ‎location through a geostatistical method using a program written in MATLAB. To evaluate ‎the efficiency of the proposed method, stochastic seismic ground responses at construction location were compared with those of the non-stationary random ‎field method‎ through real site data. The ‎results demonstrate that applying the boreholes’ ‎location significantly affects not only the ground ‎responses but also their Coefficient Of Variation (COV). Furthermore, the mean value of the seismic ‎responses is affected more considerably by the values of soil parameters at the vicinity of the construction location. It is also inferred that considering boreholes’ location may reduce the COV of the seismic ‎responses. Among the surface responses in the studied site, the values of Peak Ground Displacement (PGD) ‎and Peak Ground Acceleration (PGA) reflect the highest and ‎lowest dispersion due to uncertainties of soil ‎properties through both non-stationary random field and geostatistical methods.

The Effect of Site Condition on Ground Motion in Gansu Province during the Wenchun Ms8.0 Earthquake

2012 ◽  
Vol 594-597 ◽  
pp. 1658-1667
Author(s):  
Zhi Jian Wu ◽  
Lan Min Wang ◽  
Ping Wang ◽  
Hang Shi ◽  
Tuo Chen
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Seismic Design ◽  
Site Effects ◽  
Strong Motion ◽  
Gansu Province ◽  
Response Analysis ◽  
Site Condition ◽  
Seismic Response Analysis ◽  
Ground Acceleration

Based on mobile strong motion array observation, borehole exploration and site seismic response analysis, the site effects of mountainous topography in southeastern Gansu and the topography of loess tableland on ground motion were investigated in details. The analysis on acceleration records of aftershocks showed that the peak ground acceleration at top of the mountain is nearly 2 times of that at the foot of it. The seismic response analysis of sites shows that the loess tableland may amplify PGA by 1.44-2.0 times. Therefore, site effects of mountains and loess topography on ground motion should been taken account into seismic design.

scholarly journals Frequency-dependent site factors for the Icelandic strong-motion array from a Bayesian hierarchical model of the spatial distribution of spectral accelerations

2021 ◽  
pp. 875529302110369
Author(s):  
Sahar Rahpeyma ◽  
Benedikt Halldorsson ◽  
Birgir Hrafnkelsson ◽  
Sigurjón Jónsson
Keyword(s):  
Ground Motion ◽  
Hierarchical Model ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Bayesian Hierarchical Model ◽  
Site Factors ◽  
Ground Acceleration ◽  
Small Aperture ◽  
Bayesian Hierarchical

The earthquake ground motions of over 1700 earthquakes recorded on a small-aperture strong-motion array in south Iceland (ICEARRAY I) that is situated on a relatively uniform site condition characterized as rock, exhibit a statistically significant spatial variation of ground-motion amplitudes across the array. Both earthquake and microseismic horizontal-to-vertical spectral ratios (HVSR) have been shown to exhibit distinct and in some cases, bimodal peaks in amplification, indicating site resonance at periods of 0.1–0.3 s, a phenomenon that has been attributed to a surface layer of lava rock lying above a sedimentary layer, a structure that is then repeated with depth under the array. In this study, we implement a Bayesian hierarchical model (BHM) of the seismic ground motions that partitions the model residuals into earthquake event term, station term, and event–station term. We analyzed and compared peak ground acceleration (PGA) with the 5% damped pseudo-acceleration response spectrum (PSA) at oscillator periods of T = 0.05–1.0 s. The results show that the event terms, dominate the total variability of the ground-motion amplitudes over the array. However, the station terms are shown to increase in the period range of 0.1–0.3 s on most stations and to different extents, leading to an increase in the overall variability of ground motions at those periods, captured by a larger inter-station standard deviation. As the station terms are a measure of how much the ground motions at those stations deviate from the array average, they act as proxies for localized site effects and amplification factors. These results, improve our understanding of the key factors that affect the variation of seismic ground motions across the relatively small area of ICEARRAY I. This approach can help to improve the accuracy of earthquake hazard assessments on local scales, which in turn could contribute to more refined seismic risk assessments and engineering decision-making.

scholarly journals Equivalent-linear seismic ground response analysis in Palu area

2021 ◽  
Vol 930 (1) ◽  
pp. 012089
Author(s):  
A Jalil ◽  
T F Fathani ◽  
I Satyarno ◽  
W Wilopo
Keyword(s):  
Response Spectrum ◽  
Soil Layer ◽  
Time History ◽  
Surface Damage ◽  
Response Analysis ◽  
Infrastructure Development ◽  
Ground Response Analysis ◽  
Ground Acceleration ◽  
Soil Response ◽  
Local Soil

Abstract The 7.5 Mw Palu earthquake on September 28, 2018, was caused by the Palu Koro fault. This earthquake produced forceful wave propagation in the soil layer and generated enormous surface damage in Balaroa, Petobo, and Jono Oge. Estimations of soil amplification at a specific location are helpful as guidance for infrastructure development. This study examined the effect of local soil in modifying the one-dimensional linear soil response in Balaroa, Petobo, and Jono Oge regions, considering the data of various sites in those regions. The soil response was observed to obtain the synthetic input motion and its effects in the time history of surface acceleration, the ratio of shear stress to effective vertical stress to spectrum response time, and the Fourier amplitude versus frequency ratio. Amplification is standard for ground acceleration, which considers the strong ground motion with the acquired frequency and duration of the content. The results showed that the peak of ground acceleration amplification factors for Balaroa, Petobo, and Jono Oge was around 1.49, 2.05, and 1.27 times, respectively. With a lack of information at the particular site, designers will use the response spectrum obtained along the soil layer to develop earthquake-resistant geotechnical structures in locations close to Palu.

Dynamic Characterization and Site Response Studies for an Offshore Site Based on Detailed Geotechnical Tests

2015 ◽  
Vol 6 (1) ◽  
pp. 50-80
Author(s):  
T. G. Sitharam ◽  
Naveen James ◽  
Monalisha Nayak
Keyword(s):  
Ground Motion ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Site Characterization ◽  
Response Analysis ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Undisturbed Soil ◽  
Design Response Spectrum ◽  
Laboratory Test Results

The uniqueness of this paper is large amount of field test data and in addition laboratory test results on undisturbed soil samples, has been analyzed to capture the effect of local site condition and material properties of overlying soil on seismic ground motion characteristics. This study involves the seismic site characterization and ground response analysis of an offshore site in Western Yemen. From the results of field and laboratory tests, dynamic properties such as shear modulus and damping ratio for a very low to high strain levels was determined and site characterization was also carried out. Using seismic cone penetration test (SCPT) data a new correlation has been developed to predict the shear wave velocity. Synthetic ground motion was generated using Boore's stochastic modeling technique for ground response analysis and peak ground acceleration (PGA) was evaluated and presented in the paper. This paper also presents a site specific design response spectrum based on Eurocode, corresponding to 475 and 2500 year return period.

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