scholarly journals Ground accelerations caused by large quarry blasts

1961 ◽  
Vol 51 (2) ◽  
pp. 191-202
Author(s):  
D. E. Hudson ◽  
J. L. Alford ◽  
W. D. Iwan
Keyword(s):  
Response Spectrum ◽  
Strong Motion ◽  
Complete Response ◽  
Charge Weight ◽  
Total Charge ◽  
Ground Acceleration ◽  
Acceleration Time

Abstract Ground acceleration-time measurements have been made within 2000 ft. of two quarry blasts of total charge weight 185 tons and 673 tons. Ground accelerations were of a character and magnitude similar to those associated with damaging earthquakes. Complete response spectrum curves calculated from the acceleration records are presented. Direct comparisons are made between these results and previous similar measuements and calculations using identical instruments, which have been made of strong-motion earthquakes, H. E. blasts, and the Rainier nuclear blast.

scholarly journals Uncertainties in attenuation relations for New Zealand seismic hazard analysis

1986 ◽  
Vol 19 (1) ◽  
pp. 28-39 ◽  
Author(s):  
G. H. McVerry
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Hazard Analysis ◽  
Response Spectrum ◽  
Strong Motion ◽  
Seismic Hazard Analysis ◽  
Ground Acceleration ◽  
Attenuation Relations ◽  
Ground Shaking ◽  
Acceleration Data

Probabilistic techniques for seismic hazard analysis have
come into vogue in New Zealand for both the assessment of major projects and the development and review of seismic design codes. However, there are considerable uncertainties in the modelling
 of the strong-motion attenuation, which is necessarily based largely on overseas data. An excellent agreement is obtained between an average 5% damped response spectrum for New Zealand alluvial sites in the 20 to 59 km distance range and 5.4 to 6.0 magnitude class and that given by a Japanese model. Unfortunately, this corresponds to only about half the amplitude levels of 150 year spectra relevant to code design. The much more rapid decay
of ground shaking with distance in New Zealand has led to a considerable modification based on maximum ground acceleration
data from the Inangahua earthquake of the distance-dependence
of the Japanese response spectra model. Less scatter in New Zealand data has resulted in adopting a lower standard deviation for the attenuation model, which is important in reducing the considerable "probabilistic enhancement" of the hazard estimates. Regional differences in attenuation shown by intensities are difficult to resolve from the strong-motion acceleration data, apart from lower accelerations in Fiordland.

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.

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.

Comparison of Seismic Analysis of Jacket Structures Using Response Spectrum and Time Domain Procedures

2013 ◽  
Author(s):  
Partha Chakrabarti ◽  
Atul Rikhy
Keyword(s):  
Linear System ◽  
Ground Motion ◽  
Time Domain ◽  
Response Spectrum ◽  
Ground Acceleration ◽  
Soil System ◽  
Soil Stiffness ◽  
Acceleration Time ◽  
Acceleration Time Histories ◽  
Time Histories

In seismically active areas of the world an offshore jacket structure has to be designed for seismic loads. Since the structure must meet both strength and ductility requirements, a two stage design for Strength Level Earthquake (SLE) and Ductility Level Earthquake (DLE) is generally used. Normal procedure for designing such a structure for SLE condition is to use Response Spectrum method of analysis (RSA). The main advantage of RSA is that it is computationally very efficient. Time Domain Analysis (TDA) is used mostly to analyze DLE condition. A response spectrum depicts the maximum response to a ground motion of a single degree of freedom system having different natural periods but the same degree of damping. A design response spectrum is a smoothened average of several earthquake motions. It is a property of the ground motion with a given recurrence interval at the particular region of interest. RSA is a frequency domain analysis technique based on mode superposition approach. API RP 2A specifies that the modal responses be combined using a Complete Quadratic Combination (CQC) of modal responses. For the directional response combination, API RP 2A recommends applying 100% of the spectral acceleration for the two orthogonal lateral directions and 50% for the vertical and using the Square Root of Sum of Squares (SRSS) combination to obtain the maximum response. With this approach it is possible to conduct only one analysis, with any reference system, and the resulting structure will have all members that are designed to equally resist earthquake motions from all possible directions. RSA based on mode superposition is valid strictly for a linear system. A jacket structure with its pile-soil system is not truly a linear system due to soil nonlinearity. Therefore, linearization of the pile-soil system is necessary. The stiffness of a pile is dependent on the pile head loads. Thus the response from the RSA will be very much load or deformation dependent for the pile-soil stiffness. Software used here for the analyses has an iterative analysis option for obtaining the appropriate linearized stiffness. TDA is a step by step time integration procedure for the entire system including the piles and there is no linearization involved for the foundation stiffness as the pile-soil stiffness at discrete points of the pile are calculated at each time instant within the program. The TDA is more precise for the given time history but more time consuming as a series of ground acceleration time histories are normally required for the TDA approach. The results from RSA are expected to be conservative especially for the design of piles. However, this can only be confirmed from a series of TDA performed using ground acceleration time histories. This paper demonstrates that more accurate and less conservative results can be obtained by using a combination of RSA and TDA even for SLE condition. However, several simulations for TDA are required for confidence in the design to ensure that all structural elements have achieved the maximum conditions. Essentially, RSA can be used for jacket member design and TDA can be used specifically for pile design. Thus the authors believe the design of an entire jacket could be more economical if this combined approach is judiciously used.

THE STRONG MOTION RECORDS OF THE Ms 8.0 WENCHUAN EARTHQUAKE BY THE DIGITAL STRONG EARTHQUAKE NETWORK IN SICHUAN AND THE NEIGHBORING REGION

2011 ◽  
Vol 05 (04) ◽  
pp. 343-361 ◽  
Author(s):  
RONGJUN ZHOU ◽  
YONG LI ◽  
ALEXANDER L. DENSMORE ◽  
MIN LAI ◽  
YI ZHANG ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Response Spectrum ◽  
Hanging Wall ◽  
Strong Motion ◽  
Major Axis ◽  
Fracture Pattern ◽  
High Rate ◽  
Peak Acceleration ◽  
Ground Acceleration ◽  
Strong Motion Records

The M s 8.0 Wenchuan Earthquake of May 12, 2008 resulted in oblique dextral-thrust motion in the Longmen Shan tectonic belt resulted. During this earthquake event, 133 sets of three-component acceleration records were collected by the digital earthquake network in Sichuan Province. By using these records and some strong motion records from the networks in Shanxi and Gansu provinces, contours of peak ground acceleration were determined. These contours are elliptically shaped with the major axis oriented in a northeast direction. The peak acceleration decayed more gradually toward the northeast, parallel to the rupture propagation than toward the southwest, indicating a directivity effect. The peak acceleration also decayed more gradually toward the northwest, on the hanging wall, than toward the southeast on the footwall. A relatively high rate of attenuation in the peak acceleration was also evident on the Yingxiu-Beichuan section of the fault; this can be attributed to the seismic source fracture pattern and rupture progress. The measured peak vertical and horizontal ground acceleration components were far larger than the design values prescribed by the Code for Seismic Design of Buildings (GB50011-2001). As distance from the rupture increased, the acceleration response spectrum gradually became dominated by long-period motions. A large velocity pulse was also measured at a distance of about 80–100 km from the fault.

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.

Nonlinear Site Effects from the 30 November 2018 Anchorage, Alaska, Earthquake

2021 ◽  
Author(s):  
John D. Thornley ◽  
Utpal Dutta ◽  
John Douglas ◽  
Zhaohui (Joey) Yang
Keyword(s):  
Site Response ◽  
Strong Motion ◽  
North American Plate ◽  
Peak Ground Velocity ◽  
Reference Station ◽  
Earthquake Hazards ◽  
Ground Acceleration ◽  
Nonlinear Site Response ◽  
Generalized Inversion Technique ◽  
Versus Peak

ABSTRACT Anchorage, Alaska, is a natural laboratory for recording strong ground motions from a variety of earthquake sources. The city is situated in a tectonic region that includes the interface and intraslab earthquakes related to the subducting Pacific plate and crustal earthquakes from the upper North American plate. The generalized inversion technique was used with a local rock reference station to develop site response at >20 strong-motion stations in Anchorage. A database of 94 events recorded at these sites from 2005 to 2019 was also compiled and processed to compare their site response with those in the 2018 Mw 7.1 event (main event). The database is divided into three datasets, including 75 events prior to the main event, the main event, and 19 aftershocks. The stations were subdivided into the site classes defined in the National Earthquake Hazards Reduction Program based on estimated average shear-wave velocity in of the upper 30 m (VS30), and site-response results from the datasets were compared. Nonlinear site response was observed at class D and DE sites (VS30 of 215–300 and 150–215  m/s, respectively) but not at class CD and C sites (VS30 of 300–440 and 440–640  m/s, respectively). The relationship of peak ground acceleration versus peak ground velocity divided by VS30 (shear-strain proxy) was shown to further support the observation that sites with lower VS30 experienced nonlinear site response.

Seismic Response of Embankment Dams Based on Recorded Strong-Motion Data in Japan

2019 ◽  
Vol 35 (2) ◽  
pp. 955-976 ◽  
Author(s):  
DongSoon Park ◽  
Tadahiro Kishida
Keyword(s):  
Time Series ◽  
Seismic Response ◽  
Prediction Models ◽  
Strong Motion ◽  
Dynamic Responses ◽  
Design Stage ◽  
Ground Acceleration ◽  
Motion Data ◽  
Embankment Dams ◽  
Strong Motion Database

It is important to investigate strong-motion time series recorded at dams to understand their complex seismic responses. This paper develops a strong-motion database recorded at existing embankment dams and analyzes correlations between dam dynamic responses and ground-motion parameters. The Japan Commission on Large Dams database used here includes 190 recordings at the crests and foundations of 60 dams during 54 earthquakes from 1978 to 2012. Seismic amplifications and fundamental periods from recorded time series were computed and examined by correlation with shaking intensities and dam geometries. The peak ground acceleration (PGA) at the dam crest increases as the PGA at the foundation bedrock increases, but their ratio gradually decreases. The fundamental period broadly increases with the dam height and PGA at the foundation bedrock. The nonlinear dam response becomes more apparent as the PGA at the foundation bedrock becomes >0.2 g. The prediction models of these correlations are proposed for estimating the seismic response of embankment dams, which can inform the preliminary design stage.

scholarly journals Seismic hazard of Northern Eurasia

1999 ◽  
Vol 42 (6) ◽  
Author(s):  
V. I. Ulomov ◽  
. The GSHAP Region Working Group
Keyword(s):  
Seismic Hazard ◽  
Strong Motion ◽  
Seismic Hazard Assessment ◽  
Exceedance Probability ◽  
Hazard Mapping ◽  
Northern Eurasia ◽  
Ground Acceleration ◽  
Border Regions ◽  
Seismic Catalogue ◽  
Close Cooperation

The GSHAP Regional Centre in Moscow, UIPE, has coordinated the seismic hazard mapping for the whole territory of the former U.S.S.R. and border regions. A five-year program was conducted to assemble for the whole area, subdivided in five overlapping blocks, the unified seismic catalogue with uniform magnitude, the strong motion databank and the seismic zones model (lineament-domain-source), which form the basis of a newly developed deterministic-probabilistic computation of seismic hazard assessment. The work was conducted in close cooperation with border regions and GSHAP regional centers. The hazard was originally computed in terms of expected MSK intensity and then transformed into expected peak ground acceleration with 10% exceedance probability in 50 years.

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