scholarly journals Representative ground-motion ensembles for several major earthquake scenarios in New Zealand

2014 ◽  
Vol 47 (4) ◽  
pp. 231-252 ◽  
Author(s):  
Karim Tarbali ◽  
Brendon A. Bradley
Keyword(s):  
New Zealand ◽  
Ground Motion ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Conditional Intensity ◽  
Intensity Measure ◽  
Earthquake Scenarios ◽  
Major Earthquake ◽  
The Mean ◽  
Representative Ground

In this paper, representative ground motion ensembles for several major earthquake scenarios in New Zealand are developed. Cases considered include representative ground motions for the occurrence of Alpine, Hope and Porters Pass earthquakes in Christchurch city, and the occurrence of Wellington, Wairarapa and Ohariu fault ruptures in Wellington city. For each considered scenario rupture, ensembles of 20 and 7 ground motions are selected using the generalized conditional intensity measure (GCIM) approach, ensuring that the ground motion ensembles represent both the mean and distribution of ground motion intensity which such scenarios could impose. These scenario-based ground motion sets can be used to complement ground motions which are often selected in conjunction with probabilistic seismic hazard analysis, in order to understand the performance of structures for the question “what if this fault ruptures?”

scholarly journals Analysis of the Seismic Demand of High-Performance Buckling-Restrained Braces under a Strong Earthquake and Its Aftershocks

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Luqi Xie ◽  
Jing Wu ◽  
Qing Huang ◽  
Chao Tong
Keyword(s):  
Plastic Deformation ◽  
Ground Motion ◽  
Strong Earthquake ◽  
High Performance ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Threshold Value ◽  
Seismic Demand ◽  
Near Fault ◽  
Probabilistic Seismic Demand

The analysis of the ductility and cumulative plastic deformation (CPD) demand of a high-performance buckling-restrained brace (HPBRB) under a strong earthquake and its aftershocks is conducted in this paper. A combination of three continuous excitations with the same ground motion is used to simulate the affection of a strong earthquake and its aftershocks. A six-story HPBRB frame (HPBRBF) is taken as an example to conduct the incremental dynamic analysis (IDA). The seismic responses of the HPBRBF under one, two, and three constant continuous ground motions are compared. The IDA result indicates that the ductility and CPD demand of the BRBs under the three constant continuous ground motions are significantly larger than that excited by only one. Probabilistic seismic demand analysis (PSDA) is performed using seven near-fault ground motions and seven far-fault ground motions to consider the indeterminacy of ground motion. The probabilistic seismic demand curves (PSDCs) for the ductility and CPD demand for the HPBRB under the strong earthquake and its aftershocks are obtained in combining the probabilistic seismic hazard analysis. The results indicate that the AISC threshold value of the CPD with 200 is excessively low for a HPBRBF which suffers the continuous strong aftershocks with near-fault excitations, and a stricter threshold value should be suggested to ensure the ductility and plastic deformation capacity demand of the HPBRB.

A spectral-acceleration-based combination-type earthquake intensity measure for high-rise stack-like structures

2019 ◽  
Vol 23 (7) ◽  
pp. 1350-1366 ◽  
Author(s):  
Yikun Qiu ◽  
Changdong Zhou ◽  
Siha A ◽  
Guangwei Zhang
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Spectral Acceleration ◽  
Intensity Measure ◽  
Earthquake Intensity ◽  
Intensity Measures ◽  
Higher Modes ◽  
High Rise ◽  
Near Fault ◽  
Period Elongation

Ground motion intensity measures are of great importance for the seismic design of structures. A well-chosen intensity measure will reduce the detailed ground motion record selection effort for the nonlinear dynamic structural analyses. In this article, a spectral-acceleration-based combination-type earthquake intensity measure is presented. This intensity measure considers the higher modes effect and period elongation effect due to nonlinear deformation at the same time. The modal mass participation factors are determined to take weighting coefficients and the product of elastic first-mode period T1 and a constant C is expressed to represent the elongated period. Therefore, the proposed intensity measure is a combination of earthquake ground motion characteristics, elastic structural responses, higher modes participation, and the period elongation effect due to inelastic structural behaviors. Four three-dimensional models of reinforced concrete stack-like structures including a 240 m-high chimney, a 180 m-high chimney, a 120 m-high chimney, and a 42.3 m-high water tower are established and analyzed in ABAQUS to investigate the correlation between the intensity measure and the maximum curvatures under 44 far-field ground motions and 28 near-fault ground motions with a pulse-like effect. With the optimal vibration modes and the proper period elongation coefficient, the efficiency of the introduced intensity measure is compared with the other 15 intensity measures. The results indicate that the proposed intensity measure is believed to be a good choice for high-rise stack-like structures, especially under the near-fault ground motions with pulse-like effect.

Efficient Propagation of Epistemic Uncertainty in the Median Ground‐Motion Model in Probabilistic Hazard Calculations

2019 ◽  
Vol 109 (5) ◽  
pp. 2063-2072 ◽  
Author(s):  
Maxime Lacour ◽  
Norman A. Abrahamson
Keyword(s):  
Ground Motion ◽  
Traditional Approach ◽  
Epistemic Uncertainty ◽  
Hazard Analysis ◽  
Full Range ◽  
Motion Model ◽  
Uncertainty Distribution ◽  
Earthquake Scenarios ◽  
Ground Motion Model ◽  
Pc Method

Abstract A computationally efficient methodology for propagating the epistemic uncertainty in the median ground motion in probabilistic seismic hazard analysis is developed using the polynomial chaos (PC) approach. For this application, the epistemic uncertainty in the median ground motion for a specific scenario is assumed to be lognormally distributed and fully correlated across earthquake scenarios. In the hazard calculation, a single central ground‐motion model (GMM) is used for the median along with the epistemic standard error of the median for each scenario. A set of PC coefficients is computed for each scenario and each test ground‐motion level. The additional computation burden in computing these PC coefficients depends on the order of the approximation but is less than computing the median ground motion from one additional GMM. With the PC method, the mean and fractiles of the hazard due to the epistemic uncertainty distribution of the median ground motion are computed as a postprocess that is very fast computationally. For typical values of the standard deviation of epistemic uncertainty in the median ground motion (<0.2 natural log units), the methodology accurately estimates the epistemic uncertainty distribution of the hazard over the 1%–99% range. This full epistemic range is not well modeled with just a small number of GMM branches uses in the traditional logic‐tree approach. The PC method provides more accuracy, faster computation, and reduced memory requirements than the traditional approach. For large values of the epistemic uncertainty in the median ground motion, a higher order of the PC expansion may be needed to be included to capture the full range of the epistemic uncertainty.

Spatial Variability of Source and Attenuation Characteristics in Large Ground-Motion Datasets

2020 ◽  
Author(s):  
Sreeram Reddy Kotha ◽  
Graeme Weatherill ◽  
Dino Bindi ◽  
Fabrice Cotton
Keyword(s):  
Spatial Variability ◽  
Ground Motion ◽  
Ground Motions ◽  
Low Frequency ◽  
Strong Motion ◽  
Response Spectra ◽  
Large Datasets ◽  
Earthquake Scenarios ◽  
Crustal Earthquakes ◽  
Geographical Regions

&lt;p&gt;Ground-Motion Models (GMMs) characterize the random distributions of ground-motions for a combination of earthquake source, wave travel-path, and the effected site&amp;#8217;s geological properties. Typically, GMMs are regressed over a compendium of strong ground-motion recordings collected from several earthquakes recorded at multiple sites scattered across a variety of geographical regions. The necessity of compiling such large datasets is to expand the range of magnitude, distance, and site-types; in order to regress a GMM capable of predicting realistic ground-motions for rare earthquake scenarios, e.g. large magnitudes at short distances from a reference rock site. The European Strong-Motion (ESM) dataset is one such compendium of observations from a few hundred shallow crustal earthquakes recorded at a several hundred seismic stations in Europe and Middle-East.&lt;/p&gt;&lt;p&gt;We developed new GMMs from the ESM dataset, capable of predicting both the response spectra and Fourier spectra in a broadband of periods and frequencies, respectively. However, given the clear tectonic and geological diversity of the data, possible regional and site-specific differences in observed ground-motions needed to be quantified; whilst also considering the possible contamination of data from outliers. Quantified regional differences indicate that high-frequency ground-motions attenuate faster with distance in Italy compared to the rest of Europe, as well as systematically weaker ground-motions from central Italian earthquakes. In addition, residual analyses evidence anisotropic attenuation of low frequency ground-motions, imitating the pattern of shear-wave energy radiation. With increasing spatial variability of ground-motion data, the GMM prediction variability apparently increases. Hence, robust mixed-effects regressions and residual analyses are employed to relax the ergodic assumption.&lt;/p&gt;&lt;p&gt;Large datasets, such as the ESM, NGA-West2, and from KiK-Net, provide ample opportunity to identify and evaluate the previously hypothesized event-to-event, region-to-region, and site-to-site differences in ground-motions. With the appropriate statistical methods, these variabilities can be quantified and applied in seismic hazard and risk predictions. We intend to present the new GMMs: their development, performance and applicability, prospective improvements and research needs.&lt;/p&gt;

Exploring the Proximity of Ground-Motion Models Using High-Dimensional Visualization Techniques

2010 ◽  
Vol 26 (4) ◽  
pp. 1117-1138 ◽  
Author(s):  
Frank Scherbaum ◽  
Nicolas M. Kuehn ◽  
Matthias Ohrnberger ◽  
Andreas Koehler
Keyword(s):  
Ground Motion ◽  
Hazard Analysis ◽  
Ground Motions ◽  
High Dimensional ◽  
Logic Tree ◽  
Motion Models ◽  
Metric Set ◽  
Motion Characteristics ◽  
Visualization Techniques ◽  
Ground Motion Models

Logic trees have become a popular tool to capture epistemic uncertainties in seismic hazard analysis. They are commonly used by assigning weights to models on a purely descriptive basis (nominal scale). This invites the creation of unintended inconsistencies regarding the weights on the corresponding hazard curves. On the other hand, for human experts it is difficult to confidently express degrees-of-beliefs in particular numerical values. Here we demonstrate for ground-motion models how the model and the value-based perspectives can be partially reconciled by using high-dimensional information-visualization techniques. For this purpose we use Sammon's (1969) mapping and self-organizing mapping to project ground-motion models onto a two-dimensional map (an ordered metric set). Here they can be evaluated jointly according to their proximity in predicting similar ground motions, potentially making the assignment of logic tree weights consistent with their ground motion characteristics without having to abandon the model-based perspective.

Spectral Matching of Real Ground Motions: Applications to Horizontally Irregular Systems in Elastic Range

2014 ◽  
Vol 17 (11) ◽  
pp. 1623-1638 ◽  
Author(s):  
R. Roy ◽  
P. Thakur ◽  
S. Chakroborty
Keyword(s):  
Ground Motion ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Near Field ◽  
Spectral Matching ◽  
Uniform Hazard Spectrum ◽  
Elastic Range ◽  
Conditional Mean Spectrum ◽  
Performance Based Seismic Design ◽  
Irregular Systems

In the context of performance-based seismic design (PBSD), ground motions are often scaled to certain convenient target spectra derived from probabilistic seismic hazard analysis (PSHA). While Uniform Hazard Spectrum (UHS) is more widely used, Conditional Mean Spectrum (CMS) is recently proposed to be more desirable for scaling of real accelerograms. In this backdrop, a set of near-field and far-field ground motions are spectrally scaled, using wavelets, to both UHS and CMS. Seismic demand of horizontally irregular structures under bi-directional ground motion is assessed under both scaled and seed records in the elastic range. Spectral matching, within limits, of both the horizontal components of real records to a single hazard spectrum is observed to adequately predict the amplification in response due to asymmetry (at least for the records and target spectra relevant to soil class D). Further, such scaling effectively reduces the variability in predicted magnification from one ground motion to other. Dynamic amplification factors recommended in international codes to apply in equivalent static design of asymmetric systems are shown to be deficient.

Effect of Ground Motion Modification Technique on Seismic Geotechnical Engineering Analyses

2012 ◽  
Vol 28 (4) ◽  
pp. 1643-1661 ◽  
Author(s):  
Dimitrios Zekkos ◽  
Clinton Carlson ◽  
Ahmed Nisar ◽  
Stephanie Ebert
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
A Priori ◽  
Earthquake Scenarios ◽  
Local Site ◽  
Intensity Parameters ◽  
Target Spectrum ◽  
Modification Technique ◽  
The Time Domain ◽  
The Impact

Ground motion modification (or spectral matching) has been criticized, but has many appealing characteristics and is widely used in practice. Modification of ground motions can be performed in either the time domain or the frequency domain. Depending on the choice of modification technique, modified ground motions can be significantly different from each other as well as from the original ground motion. This paper studies the impact of these differences on seismic geotechnical analyses for two different site profiles using two earthquake scenarios and a total of 20 ground motions. This study shows that the final results are influenced by many factors such as the original (seed) ground motion, the target spectrum, and the local site conditions, in addition to the ground motion modification technique used. The results also show that while both techniques can significantly modify the original ground motion, neither technique is consistently more conservative than the other. Therefore, a general conclusion that a particular technique results in ground motions that yield the largest intensity parameters cannot be made a priori.

scholarly journals Development of synthetic ground motion at a specific site in Yogyakarta town, Indonesia utilizing the PSHA Method

2020 ◽  
Vol 156 ◽  
pp. 02011
Author(s):  
Widodo Pawirodikromo ◽  
Lalu Makrup ◽  
Mochamad Teguh ◽  
Bambang Suryo
Keyword(s):  
Pilot Study ◽  
Ground Motion ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Time History ◽  
Building Structures ◽  
Uniform Hazard Spectra ◽  
Crustal Earthquakes ◽  
History Analysis ◽  
Dynamic Time

This paper presents the development of synthetic ground motion at specific sites in Yogyakarta town. In the 2019 Indonesian Seismic Code [1] provides an alternative method in the analysis of building structures by applying the dynamic time history analysis. At least 11-pairs of earthquake recordings must be used in the analysis. Synthetic ground motion utilizing the Method of Probability Seismic Hazard Analysis (PSHA) was used in this study. A selected site in Yogyakarta town was chosen as a pilot study considering that there were many fatalities and building damage caused by the 2006 Yogyakarta earthquake. The Uniform Hazard Spectra (UHS) based on the shallow crustal earthquake source is higher than the Megathrust. The risk targeted spectrum demand MCEr has been considered, which on average 12.3% greater than the UHS. The synthetic ground motions (SGM) are accordingly based on the shallow crustal earthquakes. The dominant magnitude and distance are MD = 6.5 and RD = 14.5 km. They show that the contribution of the Opak River fault to the hazard in Yogyakarta town is very dominant because the distance is very close. Based on the obtained MD and RD, spectral matching, and testing significant duration D595, the 12-synthetic ground motions were successfully developed.

Three-Dimensional Seismic-Wave Propagation Simulations in the Southern Korean Peninsula Using Pseudodynamic Rupture Models

2021 ◽  
Author(s):  
Jaeseok Lee ◽  
Jung-Hun Song ◽  
Seongryong Kim ◽  
Junkee Rhie ◽  
Seok Goo Song
Keyword(s):  
Wave Propagation ◽  
Ground Motion ◽  
Korean Peninsula ◽  
Seismic Velocity ◽  
Ground Motions ◽  
Velocity Model ◽  
Wave Radiation ◽  
3D Seismic ◽  
Earthquake Scenarios ◽  
Large Earthquakes

ABSTRACT Accurate and practical ground-motion predictions for potential large earthquakes are crucial for seismic hazard analysis of areas with insufficient instrumental data. Studies on historical earthquake records of the Korean Peninsula suggest that damaging earthquakes are possible in the southeastern region. Yet classical ground-motion prediction methods are limited in considering the physical rupture process and its effects on ground motion in complex velocity structures. In this study, we performed ground-motion simulations based on rigorous physics through pseudodynamic source modeling and wave propagation simulations in a 3D seismic velocity model. Ensembles of earthquake scenarios were generated by emulating the one- and two-point statistics of earthquake source parameters derived from a series of dynamic rupture models. The synthetic seismograms and the distributions of simulated peak ground velocities (PGVs) were compared with the observations of the 2016 Mw 5.4 Gyeongju earthquake in the Korean Peninsula. The effects of surface-wave radiation, rupture directivity, and both local and regional amplifications from the 3D wave propagation were reproduced accurately in the spatial distribution of simulated PGVs, in agreement with the observations from dense seismic networks by mean log residuals of −0.28 and standard deviations of 0.78. Amplifications in ground motions were found in regions having low crustal velocities and in regions of constructive interference from the crustal shear-wave phases associated with postcritical reflections from the Moho discontinuity. We extended the established approach to earthquake scenarios of Mw 6.0, 6.5, and 7.0, at the same location, to provide the distribution of ground motions from potential large earthquakes in the area. Although we demonstrate the value of these simulations, improvements in the accuracy of the 3D seismic velocity model and the scaling relationship of the source models would be necessary for a more accurate estimation of near-source ground motions.

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