scholarly journals Seismic microzonation of a region with complex surficial geology based on different site classification approaches

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohammad Salsabili ◽  
Ali Saeidi ◽  
Alain Rouleau ◽  
Miroslav Nastev
Keyword(s):  
Hybrid Method ◽  
Seismic Microzonation ◽  
Site Classification ◽  
Eurocode 8 ◽  
Surficial Sediments ◽  
Rock Formations ◽  
Impedance Contrast ◽  
Average Shear ◽  
Seismic Amplification ◽  
Glaciomarine Sediments

AbstractA seismic microzonation study was conducted to refine the seismic hazard model for the city of Saguenay, Canada. The Quaternary geology underlying Saguenay shows complex glacial and post-glacial stratigraphy with a number of buried valleys filled with fluvioglacial and glaciomarine sediments. High impedance contrast between rock formations and surficial sediments is prone to seismic amplification. To evaluate their applicability, advantages and limitations in capturing the geological specificity of the study area, four site classification methods were applied: the current National Building Code of Canada (NBCC) and Eurocode 8, both mainly based on the average shear-wave velocity for the surficial sediments (VS,avg) and for the top 30 m (VS,30); a method based on the fundamental site period (T0); and a hybrid method based on the combination of VS,30, T0 and VS,avg. The study specifically aimed to evaluate the importance of the site classification parameters on the resulting microzonation maps. VS,30 is capable to present the geological and geotechnical site conditions, however, the results may be further improved by considering Vs,avg in shallow and T0 in thick layers of soil sediments as secondary parameters. The T0 method gives also satisfactory results with T0 showing a better correlation to Vs,30 than to Vs,avg. The versatile hybrid method may be challenging to apply in certain cases with its nine different site categories and parameters.

scholarly journals Geospatial Assessment of the Post-Earthquake Hazard of the 2017 Pohang Earthquake Considering Seismic Site Effects

2018 ◽  
Vol 7 (9) ◽  
pp. 375 ◽  
Author(s):  
Han-Saem Kim ◽  
Chang-Guk Sun ◽  
Hyung-Ik Cho
Keyword(s):  
Site Effects ◽  
Focal Depth ◽  
Earthquake Hazard ◽  
Earthquake Damage ◽  
Site Classification ◽  
Topographical Effects ◽  
Seismic Site Effects ◽  
Moderate Earthquake ◽  
Seismic Amplification ◽  
Earthquake Moment

The 2017 Pohang earthquake (moment magnitude scale: 5.4) was South Korea’s second strongest earthquake in decades, and caused the maximum amount of damage in terms of infrastructure and human injuries. As the epicenters were located in regions with Quaternary sediments, which involve distributions of thick fill and alluvial geo-layers, the induced damages were more severe owing to seismic amplification and liquefaction. Thus, to identify the influence of site-specific seismic effects, a post-earthquake survey framework for rapid earthquake damage estimation, correlated with seismic site effects, was proposed and applied in the region of the Pohang earthquake epicenter. Seismic zones were determined on the basis of ground motion by classifying sites using the multivariate site classification system. Low-rise structures with slight and moderate earthquake damage were noted to be concentrated in softer sites owing to the low focal depth of the site, topographical effects, and high frequency range of the mainshocks.

scholarly journals A Comparative Study on the VS30 and N30 Based Seismic Site Classification in Kahramanmaras, Turkey

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Dalia Munaff Naji ◽  
Muge K. Akin ◽  
Ali Firat Cabalar
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Soil Structure ◽  
Site Response ◽  
Dead Sea ◽  
Site Classification ◽  
Earthquake Hazards ◽  
Class D ◽  
Average Shear

Assessment of seismic site classification (SSC) using either the average shear wave velocity (VS30) or the average SPT-N values (N30) for upper 30 m in soils is the simplest method to carry out various studies including site response and soil-structure interactions. Either the VS30- or the N30-based SSC maps designed according to the National Earthquake Hazards Reduction Program (NEHRP) classification system are effectively used to predict possible locations for future seismic events. The main goal of this study is to generate maps using the Geographic Information System (GIS) for the SSC in Kahramanmaras city, influenced by both East Anatolian Fault and Dead Sea Fault Zones, using both VS30 and N30 values. The study also presents a series of GIS maps produced using the shear wave velocity (VS) and SPT-N values at the depths of 5 m, 10 m, 15 m, 20 m, and 25 m. Furthermore, the study estimates the bed rock level and generates the SSC maps for the average VS values through overburden soils by using the NEHRP system. The VS30 maps categorize the study area mainly under class C and limited number of areas under classes B and D, whereas the N30 maps classify the study area mainly under class D. Both maps indicate that the soil classes in the study area are different to a high extent. Eventually, the GIS maps complied for the purpose of urban development may be utilized effectively by engineers in the field.

scholarly journals Investigation of Soil Characterization in Hatay Province in Turkey by Using Seismic Refraction, Multichannel Analysis of Surface Waves and Microtremor

2021 ◽  
Vol 24 (4) ◽  
pp. 473-484
Author(s):  
Cengiz Kurtuluş ◽  
Ibrahim Sertcelik ◽  
Fadime Sertçelik ◽  
Hamdullah Livaoğlu ◽  
Cüneyt Şaş
Keyword(s):  
Surface Waves ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Seismic Refraction ◽  
Strong Motion ◽  
Site Classification ◽  
Eurocode 8 ◽  
Site Class ◽  
Multichannel Analysis

In this study, shallow seismic surveys, including seismic refraction, Multichannel Analysis of Surface Waves (MASW), Refraction Microtremor (ReMi), and Microtremor measurements were conducted to estimate site characterization at 26 strong-motion stations of AFAD (Disaster and Emergency Management Presidency) in the province of Hatay, situated in one of the most seismically active regions in southern Turkey. The Horizontal to vertical spectral ratio (HVSR) technique was applied, using smoothed Fourier spectra derived from a long duration series to determine dominant frequency values at different amplification levels. Shear wave velocity up to 30 m of the ground was detected with MASW analysis. In the ReMi analysis, up to 80 m was reached with a corresponding average of 650 m/s shear wave velocity. The shear wave velocities estimated by the MASW method up to 30 m were compared with those found by the ReMi method, and they were observed to be very compatible. The province of Hatay was classified according to Vs30 based NEHRP Provisions, Eurocode-8, the Turkish Building Earthquake Regulation (TBDY-2018), and Rodriguez-Marek et al. (2001). The shear-wave velocity (Vs30), Horizontal to Vertical ratio’s (H/V) peak amplitude, dominant period, and site class of each site were determined. The H/V peak amplitudes range between 1.9 and 7.6, while the predominant periods vary from 0.23 sec to 2.94sec in the study area. These results are investigated to explain the consistency of site classification schemes.

Seismic Microzonation and Site Effects Detection Through Microtremors Measures

2018 ◽  
pp. 326-349
Author(s):  
Francisco Alberto Calderon ◽  
Emilce Gisela Giolo ◽  
Carlos Daniel Frau ◽  
Marcelo Gerardo Jesús Guevara Rengel ◽  
Hernan Rodriguez ◽  
...  
Keyword(s):  
Site Effects ◽  
Amplification Factor ◽  
Seismic Microzonation ◽  
Poor Countries ◽  
Advantages And Disadvantages ◽  
Cheap Method ◽  
Hvsr Method ◽  
Seismic Amplification ◽  
Fundamental Reason ◽  
Well Correlation

Seismic microzonation of a city can be a difficult and expensive undertaking depending on the method used. In the last years, the HVSR method has been one of the most popular ways to define the natural frequency of the soil and seismic amplification factor in order to make quick microzonations due to that it is an expeditious and cheap method. This is very important in developing countries and poor countries. The fundamental reason to use this method is the fact that the amplification factor has well correlation with damage distribution. Additionally with the help of another methods it is possible obtain the structure of the superficial soil strata. In this chapter, an introduction with seismic microzonation, site effects concepts, microtremors, description of the HVSR method, advantages and disadvantages of this method, limitations and comparison with other methods, are presented. Finally, highlight of the importance of the method in order to identify site effects are displayed as examples and the incorporation of these data to Geographic Information Systems is also shown.

A Comparative Study of Design Base Shear for RC Buildings in Selected Seismic Design Codes

2012 ◽  
Vol 28 (3) ◽  
pp. 1047-1070 ◽  
Author(s):  
Vijay Namdev Khose ◽  
Yogendra Singh ◽  
Dominik H. Lang
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Cumulative Effect ◽  
Building Design ◽  
Site Classification ◽  
Eurocode 8 ◽  
Design Codes ◽  
Base Shear ◽  
Rc Buildings ◽  
Design Response Spectrum

Modern seismic building design codes tend to converge on issues of design methodology and the state-of-the-art. However, significant differences exist in basic provisions of various codes. This paper compares important provisions related to the seismic design of RC buildings in some of the major national seismic building codes viz. ASCE 7, Eurocode 8, NZS 1170.5, and IS 1893. Code provisions regarding the specification of hazard, site classification, design response spectrum, ductility classification, response reduction factors, and minimum design base shear are compared and their cumulative effect on design base shear is studied. The objective component of overstrength contributed by the material and load factors is considered to normalize the design base shear. It is observed that every code has merit over the other codes in some aspect. The presented discussion highlights the major areas of differences which need attention in the process of harmonization of different codes of the world.

scholarly journals NEHRP Site Classification and Preliminary Soil Amplification Maps of Lamphun City, Northern Thailand

2016 ◽  
Vol 8 (1) ◽  
Author(s):  
Thanop Thitimakorn ◽  
Thanabodi Raenak
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Soil Classification ◽  
Site Classification ◽  
Soil Amplification ◽  
Northern Thailand ◽  
Average Shear

AbstractThe primary goal of this study is to generate the NEHRP soil classification map for Lamphun City using the average shear wave velocity values (Vs

scholarly journals Vs30Estimate for Southwest China

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Yan Yu ◽  
Walter J. Silva ◽  
Bob Darragh ◽  
Xiaojun Li
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Southwest China ◽  
Strong Motion ◽  
Site Classification ◽  
Borehole Data ◽  
Data Set ◽  
Average Shear ◽  
Shear Wave Velocity Profile

Several methods were used to estimateVs30from site profiles with borehole depths of about 20 m for the strong-motion stations located in Southwest China. The methods implemented include extrapolation (constant and gradient), Geomatrix Site Classification correlation with shear-wave velocity, and remote sensing (terrain and topography). The gradient extrapolation is the preferred choice of this study for sites with shear-wave velocity profile data. However, it is noted that the coefficients derived from the California data set are not applicable to sites in Southwest China. Due to the scarcity of borehole profiles data with depth of more than 30 m in Southwest China, 73 Kiknet profiles were used to generate new coefficients for gradient extrapolation. Fortunately, these coefficients provide a reasonable estimate ofVs30for sites in Southwest China. This study showedVs30could be estimated by the time-average shear-wave velocity (average slowness) of only 10 meters of depth. Furthermore, a medianVs30estimate based upon Geomatrix Classification is derived from the results of the gradient extrapolation using a regional calibration of the Geomatrix Classification withVs30. The results of this study can be applied to assignVs30to the sites without borehole data in Southwest China.

scholarly journals Developing Earthquake-Resistant Structural Design Standard for Malaysia Based on Eurocode 8: Challenges and Recommendations

Standards ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 134-153
Author(s):  
Daniel Looi ◽  
Nelson Lam ◽  
Hing-Ho Tsang
Keyword(s):  
Seismic Hazard ◽  
Dynamic Analysis ◽  
Structural Design ◽  
Classification Scheme ◽  
National Standard ◽  
Probabilistic Seismic Hazard Assessment ◽  
Site Classification ◽  
Eurocode 8 ◽  
Natural Period ◽  
Moderate Seismicity

In late 2017, the Malaysian National Annex (NA) to Eurocode 8 (EC8) was released and enacted following some 13 years of deliberations and preparations. The authors of this paper aim to use this article to share their experiences and reflections during this period of developing the first national standard for the seismic design of buildings for Malaysia. To begin with, there were major challenges in implementing the 20-year-old EC8 framework for a country so far away from Europe. The first challenge was adapting the probabilistic seismic hazard assessment (PSHA) methodology in a low-to-moderate seismicity region where the paucity of representative seismic data presented a great deal of uncertainties. To address this situation, imposing a minimum level of seismic hazard was recommended. The second challenge was about dealing with the outdated EC8 site classification scheme, which poorly represents the potential effects of soil amplification in certain geological settings. To address this situation, an alternative site classification scheme in which the site natural period is an explicit modelling parameter was introduced. The third challenge was concerned with difficulties generated by the EC8 provisions mandating Ductility Class Medium (DCM) detailing in certain localities where the level of seismic hazard is predicted to exceed a certain threshold. To address this situation, the viable option of using strength to trade off for ductility was recommended, or in cases where ductility design is needed, a simplified set of code-compliant DCM designs was presented. The fourth challenge was about handling the requirements of EC8 that the majority of buildings are to involve dynamic analysis in their structural design when the majority of practising professionals did not have the skills of exercising proper use of the requisite software. To address this situation, a generalized force method was introduced to control the use dynamic analysis in commercial software. It is hoped that, through sharing the lessons learnt, code drafters for the future would be able to find ways of circumventing the multitude of challenges with clear thinking and pragmatism.

Application of the Neo-Deterministic Seismic Microzonation Procedure in Bulgaria and Validation of the Seismic Input Against Eurocode 8

2008 ◽  
Author(s):  
Paskaleva Ivanka ◽  
Kouteva Mihaela ◽  
Vaccari Franco ◽  
Panza Giuliano F. ◽  
Adolfo Santini ◽  
...  
Keyword(s):  
Seismic Microzonation ◽  
Eurocode 8 ◽  
Seismic Input
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