A subset of CyberShake ground-motion time series for response-history analysis

2021 ◽  
pp. 875529302098197
Author(s):  
Jack W Baker ◽  
Sanaz Rezaeian ◽  
Christine A Goulet ◽  
Nicolas Luco ◽  
Ganyu Teng
Keyword(s):  
Time Series ◽  
Los Angeles ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Motion Time ◽  
History Analysis ◽  
Response History Analysis ◽  
Simulated Ground Motions

This manuscript describes a subset of CyberShake numerically simulated ground motions that were selected and vetted for use in engineering response-history analyses. Ground motions were selected that have seismological properties and response spectra representative of conditions in the Los Angeles area, based on disaggregation of seismic hazard. Ground motions were selected from millions of available time series and were reviewed to confirm their suitability for response-history analysis. The processes used to select the time series, the characteristics of the resulting data, and the provided documentation are described in this article. The resulting data and documentation are available electronically.

Evaluation of Hybrid Broadband Ground Motion Simulations for Response History Analysis and Design

2015 ◽  
Vol 31 (3) ◽  
pp. 1691-1710 ◽  
Author(s):  
Lynne S. Burks ◽  
Reid B. Zimmerman ◽  
Jack W. Baker
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Spectral Response ◽  
Analysis And Design ◽  
History Analysis ◽  
Response History Analysis ◽  
Simulated Ground Motions ◽  
Broadband Ground Motion ◽  
New Buildings ◽  
Selection Of

Chapter 16 of ASCE 7 governs the selection of ground motions for analysis of new buildings and requires recordings that meet specified criteria. If a sufficient number of recordings cannot be found, it allows the use of “appropriate simulated ground motions,” but does not provide further guidance. This paper outlines a procedure for generating and selecting a set of “appropriate” hybrid broadband simulations and a comparable set of recordings. Both ground motion sets are used to analyze a building in Berkeley, California, and the predicted structural performance is compared. The structural behavior resulting from recordings and simulations is similar, and most discrepancies are explained by differences in directional properties such as orientation of the maximum spectral response. These results suggest that when simulations meet the criteria outlined for recordings in ASCE 7 and properties such as directionality are realistically represented, simulations provide useful results for structural analysis and design.

Conditioned Simulation of Ground-Motion Time Series at Uninstrumented Sites Using Gaussian Process Regression

2021 ◽  
Author(s):  
Aidin Tamhidi ◽  
Nicolas Kuehn ◽  
S. Farid Ghahari ◽  
Arthur J. Rodgers ◽  
Monica D. Kohler ◽  
...  
Keyword(s):  
Time Series ◽  
Gaussian Process ◽  
Ground Motion ◽  
San Francisco ◽  
Earthquake Engineering ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Free Field ◽  
Gaussian Process Regression ◽  
Motion Time

ABSTRACT Ground-motion time series are essential input data in seismic analysis and performance assessment of the built environment. Because instruments to record free-field ground motions are generally sparse, methods are needed to estimate motions at locations with no available ground-motion recording instrumentation. In this study, given a set of observed motions, ground-motion time series at target sites are constructed using a Gaussian process regression (GPR) approach, which treats the real and imaginary parts of the Fourier spectrum as random Gaussian variables. Model training, verification, and applicability studies are carried out using the physics-based simulated ground motions of the 1906 Mw 7.9 San Francisco earthquake and Mw 7.0 Hayward fault scenario earthquake in northern California. The method’s performance is further evaluated using the 2019 Mw 7.1 Ridgecrest earthquake ground motions recorded by the Community Seismic Network stations located in southern California. These evaluations indicate that the trained GPR model is able to adequately estimate the ground-motion time series for frequency ranges that are pertinent for most earthquake engineering applications. The trained GPR model exhibits proper performance in predicting the long-period content of the ground motions as well as directivity pulses.

Evaluation of Earthquake Response Spectra Directionality Using Stochastic Simulations

2021 ◽  
Author(s):  
Alan Poulos ◽  
Eduardo Miranda ◽  
Jack W. Baker
Keyword(s):  
Stochastic Process ◽  
Ground Motion ◽  
Ground Motions ◽  
Gaussian White Noise ◽  
Response Spectra ◽  
Orientation Dependence ◽  
Stochastic Simulations ◽  
Earthquake Ground Motion ◽  
Significant Duration ◽  
Simulated Ground Motions

ABSTRACT For earthquake-resistant design purposes, ground-motion intensity is usually characterized using response spectra. The amplitude of response spectral ordinates of horizontal components varies significantly with changes in orientation. This change in intensity with orientation is commonly known as ground-motion directionality. Although this directionality has been attributed to several factors, such as topographic irregularities, near-fault effects, and local geologic heterogeneities, the mechanism behind this phenomenon is still not well understood. This work studies the directionality characteristics of earthquake ground-motion intensity using synthetic ground motions and compares their directionality to that of recorded ground motions. The two principal components of horizontal acceleration are sampled independently using a stochastic model based on finite-duration time-modulated filtered Gaussian white-noise processes. By using the same stochastic process to sample both horizontal components of motion, the variance of horizontal ground acceleration has negligible orientation dependence. However, these simulations’ response spectral ordinates present directionality levels comparable to those found in real ground motions. It is shown that the directionality of the simulated ground motions changes for each realization of the stochastic process and is a consequence of the duration being finite. Simulated ground motions also present similar directionality trends to recorded earthquake ground motions, such as the increase of average directionality with increasing period of vibration and decrease with increasing significant duration. These results suggest that most of the orientation dependence of horizontal response spectra is primarily explained by the finite significant duration of earthquake ground motion causing inherent randomness in response spectra, rather than by some physical mechanism causing polarization of shaking.

Evaluation of SCEC CyberShake Ground Motions for Engineering Practice

2019 ◽  
Vol 35 (3) ◽  
pp. 1311-1328 ◽  
Author(s):  
Ganyu Teng ◽  
Jack Baker
Keyword(s):  
Los Angeles ◽  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Building Design ◽  
Empirical Models ◽  
Soil Conditions ◽  
Engineering Practice ◽  
Ground Motion Selection ◽  
Promising Source

This paper evaluates CyberShake (version 15.12) ground motions for potential application to high-rise building design in the Los Angeles region by comparing them against recordings from past earthquakes as well as empirical models. We consider two selected sites in the Los Angeles region with different underlying soil conditions and select comparable suites of ground motion records from CyberShake and the NGA-West2 database according to the ASCE 7-16 requirements. Major observations include (1) selected ground motions from CyberShake and NGA-West2 share similar features, in terms of response spectra and polarization; (2) when selecting records from Cyber-Shake, it is easy to select motions with sources that match the hazard deaggregation; (3) CyberShake durations on soil are consistent with the empirical models considered, whereas durations on rock are slightly shorter; (4) occasional excessive polarization in ground motion is produced by San Andreas fault ruptures, though those records are usually excluded after the ground motion selection. Results from this study suggest that CyberShake ground motions are a suitable and promising source of ground motions for engineering evaluations.

Evaluation of Building Collapse Risk and Drift Demands by Nonlinear Structural Analyses Using Conventional Hazard Analysis versus Direct Simulation with CyberShake Seismograms

2019 ◽  
Vol 109 (5) ◽  
pp. 1812-1828 ◽  
Author(s):  
Nenad Bijelić ◽  
Ting Lin ◽  
Gregory G. Deierlein
Keyword(s):  
Los Angeles ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Tall Buildings ◽  
Direct Analysis ◽  
Large Magnitude ◽  
Deep Basin ◽  
Building Collapse ◽  
Nonlinear Structural

Abstract Limited data on strong earthquakes and their effect on structures pose challenges of making reliable risk assessments of tall buildings. For instance, although the collapse safety of tall buildings is likely controlled by large‐magnitude earthquakes with long durations and high low‐frequency content, there are few available recorded ground motions to evaluate these issues. The influence of geologic basins on amplifying ground‐motion effects raises additional questions. Absent recorded motions from past large magnitude earthquakes, physics‐based ground‐motion simulations provide a viable alternative. This article examines collapse risk and drift demands of a 20‐story archetype tall building using ground motions at four sites in the Los Angeles (LA) basin. Seismic demands of the building are calculated form nonlinear structural analyses using large datasets (∼500,000 ground motions per site) of unscaled, site‐specific simulated seismograms. Seismic hazard and building performance from direct analysis of Southern California Earthquake Center CyberShake motions are contrasted with values obtained based on conventional approaches that rely on recorded motions coupled with probabilistic seismic hazard assessments. At the LA downtown site, the two approaches yield similar estimates of mean annual frequency of collapse (λc), whereas nonlinear drift demands estimated with direct analysis are slightly larger primarily because of differences in hazard curves. Conversely, at the deep basin site, the CyberShake‐based analysis yields around seven times larger λc than the conventional approach, and both hazard and spectral shapes of the motions drive the differences. Deaggregation of collapse risk is used to identify the relative contributions of causal earthquakes, linking building responses with specific seismograms and contrasting collapse risk with hazard. A strong discriminative power of average spectral acceleration and significant duration for predicting collapse is observed.

scholarly journals A Procedure to Select Earthquake Time Histories for Deterministic Seismic Hazard Analysis: Case Studies of Major Cities in Taiwan

2017 ◽  
Author(s):  
Duruo Huang ◽  
Wenqi Du
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Surface ◽  
Strong Motion ◽  
Response Spectra ◽  
Dynamic Responses ◽  
Motion Time ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Deterministic Seismic Hazard

Abstract. In performance-based seismic design, ground-motion time histories are needed for analyzing dynamic responses of nonlinear structural systems. However, the number of strong-motion data at design level is often limited. In order to analyze seismic performance of structures, ground-motion time histories need to be either selected from recorded strong-motion database, or numerically simulated using stochastic approaches. In this paper, a detailed procedure to select proper acceleration time histories from the Next Generation Attenuation (NGA) database for several cities in Taiwan is presented. Target response spectra are initially determined based on a local ground motion prediction equation under representative deterministic seismic hazard analyses. Then several suites of ground motions are selected for these cities using the Design Ground Motion Library (DGML), a recently proposed interactive ground-motion selection tool. The selected time histories are representatives of the regional seismic hazard, and should be beneficial to earthquake studies when comprehensive seismic hazard assessments and site investigations are yet available. Note that this method is also applicable to site-specific motion selections with the target spectra near the ground surface considering the site effect.

Significance of Ground Motion Scaling Parameters on Amplitude of Scale Factors and Seismic Response of Short- and Long-Period Structures

2019 ◽  
Vol 35 (4) ◽  
pp. 1663-1688 ◽  
Author(s):  
Esengul Cavdar ◽  
Gokhan Ozdemir ◽  
Beyhan Bayhan
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Scaling Method ◽  
Period Range ◽  
Long Period ◽  
Scale Factors ◽  
Short Period ◽  
Response History Analysis

In this study, an ensemble of ground motions is selected and scaled in order to perform code-compliant bidirectional Nonlinear Response History Analysis for the design purpose of both short- and long-period structures. The followed scaling method provides both the requirements of the Turkish Earthquake Code regarding the scaling of ground motions and compatibility of response spectra of selected ground motion pairs with the target spectrum. The effects of four parameters, involved in the followed scaling method, on both the amplitude of scale factors and seismic response of structures are investigated. These parameters are the number of ground motion records, period range, number of periods used in the related period range, and distribution of weight factors at the selected periods. In the analyses, ground motion excitations were applied to both fixed-base and seismically isolated structure models representative of short- and long-period structures, respectively. Results revealed that both the amplitudes of scale factors and seismic response of short-period structures are more prone to variation of investigated parameters compared to those of long-period structures.

Basin waves on a seafloor recording of the 1990 Upland, California, earthquake: Implications for ground motions from a larger earthquake

1999 ◽  
Vol 89 (1) ◽  
pp. 317-324
Author(s):  
David M. Boore
Keyword(s):  
Time Series ◽  
Wave Propagation ◽  
Los Angeles ◽  
Surface Waves ◽  
Ground Motions ◽  
Response Spectra ◽  
Theoretical Models ◽  
Regression Equations ◽  
Los Angeles Basin ◽  
Basin Response

Abstract The velocity and displacement time series from a recording on the seafloor at 74 km from the 1990 Upland earthquake (M = 5.6) are dominated by late-arriving waves with periods of 6 to 7 sec. These waves are probably surface waves traveling across the Los Angeles basin. Response spectra for the recording are in agreement with predictions from empirical regression equations and theoretical models for periods less than about 1 sec but are significantly larger than those predictions for longer periods. The longer-period spectral amplitudes are controlled by the late-arriving waves, which are not included in the theoretical models and are underrepresented in the data used in the empirical analyses. When the motions are scaled to larger magnitude, the results are in general agreement with simulations of wave propagation in the Los Angeles basin by Graves (1998).

scholarly journals Orientation effects of horizontal seismic components on longitudinal reinforcement in R/C frame elements

2012 ◽  
Vol 12 (1) ◽  
pp. 1-10 ◽  
Author(s):  
K. G. Kostinakis ◽  
A. M. Athanatopoulou ◽  
I. E. Avramidis
Keyword(s):  
Ground Motion ◽  
Cross Sections ◽  
Linear Response ◽  
Ground Motions ◽  
Longitudinal Reinforcement ◽  
Analysis And Design ◽  
History Analysis ◽  
Response History Analysis ◽  
Internal Forces ◽  
Horizontal Ground Motion

Abstract. The present paper investigates the influence of the orientation of recorded horizontal ground motion components on the longitudinal reinforcement of R/C frame elements within the context of linear response history analysis. For this purpose, three single-story buildings are analyzed and designed for 13 recorded bi-directional ground motions applied along the horizontal structural axes. The analysis and design is performed for several orientations of the recording angle of the horizontal seismic components. For each orientation the longitudinal reinforcement at all critical cross sections is calculated using four methods of selecting the set of internal forces needed to compute the required reinforcement. The results show that the reinforcement calculated by three of the applied methods is significantly affected by the orientation of the recording angle of ground motion, while the fourth one leads to results which are independent of the orientation of the recording angle.

Compatible ground-motion time histories for new national seismic hazard maps

1998 ◽  
Vol 25 (2) ◽  
pp. 305-318 ◽  
Author(s):  
Gail M Atkinson ◽  
Igor A Beresnev
Keyword(s):  
British Columbia ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Hazard Maps ◽  
Probability Level ◽  
Seismic Hazard Maps ◽  
Motion Time ◽  
Time Histories ◽  
Canadian Council

Ground-motion time histories which are compatible with the uniform hazard spectra (UHS) provided by the new national seismic hazard maps of the Geological Survey of Canada (GSC) are simulated. Time histories are simulated for the following cities: Halifax, La Malbaie, Québec, Montreal, Ottawa, Toronto, Prince George, Tofino, Vancouver, and Victoria. The target UHS for the time history simulations are the GSC 5% damped horizontal-component spectra for "firm ground" (Class B) sites for an annual probability of 1/500. The Canadian Council on Earthquake Engineering is currently considering the adoption of these maps as the seismological basis for the earthquake design requirements for future editions of the National Building Code of Canada. It is therefore useful to have compatible time histories for these spectra, in order that dynamic analysis methods requiring the use of time histories can be employed. The simulated records provide a realistic representation of ground motion for the earthquake magnitudes and distances that contribute most strongly to hazard at the selected cities and probability level. For each selected city, two horizontal components are generated for a moderate earthquake nearby, and two horizontal components are generated for a larger earthquake farther away. These records match the short- and long-period ends of the target UHS, respectively. These simulations for local and regional crustal earthquakes are based on a point-source stochastic simulation procedure. For cities in British Columbia, records are also simulated for a scenario M8.5 earthquake on the Cascadia subduction zone, using a stochastic finite-fault simulation model. Four different rupture scenarios are considered. The ground motions for this scenario event are not associated with a specific probability level, but current information suggests that their probability of occurrence is comparable to that of the 1/500 UHS (the probabilistic analyses performed for the national hazard maps do not explicitly include the Cascadia subduction event). Thus it would be reasonable to conduct engineering analyses for cities in British Columbia using both the simulated crustal-event motions and the simulated Cascadia-event motions for the Cascadia event. The time histories simulated for this study are available free of charge to all interested parties.Key words: compatible time-histories, seismic hazard, ground motions.

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