Bi-Directional Pseudo-Acceleration Response Spectra

2016 ◽  
Vol 10 (04) ◽  
pp. 1650007
Author(s):  
Anat Ruangrassamee ◽  
Chitti Palasri ◽  
Panitan Lukkunaprasit
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Response Spectra ◽  
Acceleration Response ◽  
Acceleration Response Spectra ◽  
Acceleration Response Spectrum ◽  
Two Degree Of Freedom ◽  
Ratio Response

In seismic design, excitations are usually considered separately in two perpendicular directions of structures. In fact, the two components of ground motions occur simultaneously. This paper clarifies the effects of bi-directional excitations on structures and proposes the response spectra called “bi-directional pseudo-acceleration response spectra”. A simplified analytical model of a two-degree-of-freedom system was employed. The effect of directivity of ground motions was taken into account by applying strong motion records in all directions. The analytical results were presented in the form of the acceleration ratio response spectrum defined as the bi-directional pseudo-acceleration response spectrum normalized by a pseudo-acceleration response spectrum.

Smooth Acceleration Spectra for Pulse-Like Ground Motions

2020 ◽  
Vol 110 (6) ◽  
pp. 2755-2765
Author(s):  
Cuihua Li ◽  
Guofeng Xue ◽  
Zhanxuan Zuo
Keyword(s):  
Seismic Design ◽  
Amplification Factor ◽  
Response Spectrum ◽  
Ground Motions ◽  
Response Spectra ◽  
Acceleration Response ◽  
Constant Acceleration ◽  
Step Procedure ◽  
Acceleration Response Spectrum ◽  
Smooth Acceleration

ABSTRACT Idealization of acceleration response spectra is the basis for construction of target spectra for seismic design and assessment of structures. The adequacy of current methods to reasonably idealize (or smooth) the acceleration spectra of pulse-like and nonpulse-like ground motions is examined in this study. The influence of separated pulses on different regions of acceleration response spectrum is first investigated using wavelet transform. One representative method is selected as the benchmark to examine the effectiveness of the Newmark–Hall-based methods to smooth the acceleration spectra of pulse-like and nonpulse-like ground motions. Presented are some important insights into why the plateau (or amplification factor) associated with the constant-acceleration branch may be underestimated and the ending cutoff period Tg be overestimated by Newmark–Hall-based methods. This study highlights the intrinsic characteristics and the importance of the constant-acceleration branch, based on which a two-step procedure is proposed to idealize the acceleration spectra. The results show that the proposed methodology can accurately identify the constant-acceleration branch regardless of the influence of pulses on the descending branch of acceleration spectra.

A Semi-Automated Procedure for Selecting and Scaling Recorded Earthquake Motions for Dynamic Analysis

2008 ◽  
Vol 24 (4) ◽  
pp. 911-932 ◽  
Author(s):  
Albert Kottke ◽  
Ellen M. Rathje
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Ground Motions ◽  
Acceleration Response ◽  
Analysis Process ◽  
Target Spectrum ◽  
Acceleration Response Spectrum ◽  
Individual Scale ◽  
The Individual ◽  
Selection Of

Suites of earthquake ground motions play an important role in the seismic design and analysis process. A semi-automated procedure is described that selects and scales ground motions to fit a target acceleration response spectrum, while at the same time the procedure controls the variability within the ground motion suite. The basic methodology selects motions based on matching the target spectral shape, and then fits the amplitude and standard deviation of the target by adjusting the individual scale factors for the motions. The selection of motions from a larger catalog of motions is performed through either a rigorous method that tries each possible suite of motions or an iterative approach that considers a smaller set of potential suites in an effort to find suites that provide an acceptable fit to the target spectrum. Guidelines are provided regarding the application of the developed procedures, and example applications are described.

Effects of Earthquake Source, Path, and Site Conditions on Damping Modification Factor for the Response Spectrum of the Horizontal Component from Subduction Earthquakes

2019 ◽  
Vol 109 (6) ◽  
pp. 2594-2613 ◽  
Author(s):  
John X. Zhao ◽  
Qingsong Yang ◽  
Kaiwei Su ◽  
Jiguan Liang ◽  
Jun Zhou ◽  
...  
Keyword(s):  
Statistical Tests ◽  
Response Spectrum ◽  
Source Parameters ◽  
Response Spectra ◽  
Earthquake Source ◽  
Horizontal Component ◽  
Site Conditions ◽  
Acceleration Response ◽  
Acceleration Response Spectra ◽  
Earthquake Source Parameters

Abstract Damping modification factors (DMFs) are important for estimating the response spectrum for the design of structures with different damping ratios. This study investigated the effects of earthquake source parameters (magnitude, source depth, and source categories), source distance (the closest distance from a site to a fault plane for large earthquakes and hypocentral distance for the other events), and site conditions on DMFs for the displacement and acceleration response spectra of the horizontal components of the records from Japan. This study used a total of 14,713 strong‐motion records from the KiK‐net and K‐NET to compare the DMFs from three earthquake category groups, namely shallow crustal and upper mantle, subduction interface, and subduction slab earthquakes. Statistical tests were carried out to determine whether the DMFs from these three types of earthquakes differ significantly from each other. The test results show that, between each pair of the three types of earthquakes, the DMFs for both displacement and acceleration response spectra differ significantly in terms of statistical tests and practically for engineering applications at many spectral periods, with the largest difference over 40%. The effects of earthquake category and site conditions for acceleration spectrum are similar to those of the displacement spectrum at short periods up to about 0.3 s but are much larger than those of the displacement spectrum at long spectral periods. The effects of magnitude and earthquake depth are also significant. Therefore, separate DMF models for the response spectrum of the horizontal component should be derived for each type of earthquake and should account for the effects of earthquake source and path parameters and site conditions.

scholarly journals Estimation of strong ground motions in Mexico City expected for large earthquakes in the Guerrero seismic gap

1993 ◽  
Vol 83 (3) ◽  
pp. 811-829 ◽  
Author(s):  
Hiroo Kanamori ◽  
Paul C. Jennings ◽  
Shri Krishna Singh ◽  
Luciana Astiz
Keyword(s):  
Ground Motion ◽  
Mexico City ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Response Spectra ◽  
Simulation Method ◽  
Propagation Path ◽  
Seismic Gap ◽  
Large Earthquakes

Abstract We performed simulations of ground motions in Mexico City expected for large earthquakes in the Guerrero seismic gap in Mexico. The simulation method uses as empirical Green's functions the accelerograms recorded in Mexico City during four small to moderate earthquakes (8 Feb. 1988, Ms = 5.8; 25 April 1989, Mw = 6.9; 11 May 1990, Mw = 5.5; and 31 May 1990, Mw = 6.0) in the Guerrero gap. Because these events occurred in the Guerrero gap, and have typical thrust mechanisms, the propagation path and site effects can be accurately included in our simulation. Fault rupture patterns derived from the 1985 Michoacan earthquake and source scaling relations appropriate for Mexican subduction zone earthquakes are used. If the Guerrero event is similar to the 1985 Michoacan event, the resulting response spectrum in Mexico City will be approximately twice as large as that of the 1985 Michoacan earthquake at periods longer than 2 sec. At periods shorter than 2 sec, the amplitude will be 2 to 3 times larger than that for the Michoacan earthquake. If the events in the Guerrero seismic gap occur as a sequence of magnitude 7.5 to 7.8 events, as they did in the previous sequence around the turn of the century, the strong motion in Mexico City is estimated to be about half that experienced during the 1985 Michoacan earthquake at periods longer than 2 sec. However, several factors affect this estimate. The magnitude of the possible events has a significant range and, if a rupture sequence is such that it enhances ground-motion amplitude with constructive interference, as occurred during the second half of the Michoacan sequence, some components of the ground motion could be amplified by a factor of 2 to 3. To aid in the interpretation of the simulated motion for purposes of design or hazard assessment, design spectra for the CDAO site in Mexico City are derived from the response spectra of the simulated ground motions.

scholarly journals Near-source strong ground motions observed in the 22 February 2011 Christchurch earthquake

2011 ◽  
Vol 44 (4) ◽  
pp. 181-194 ◽  
Author(s):  
Brendon A. Bradley ◽  
Misko Cubrinovski
Keyword(s):  
Surface Waves ◽  
Site Response ◽  
Ground Motions ◽  
Response Spectra ◽  
Critical Examination ◽  
Acceleration Response ◽  
Strong Ground Motions ◽  
Nonlinear Site Response ◽  
Acceleration Response Spectra ◽  
Strong Ground

This manuscript provides a critical examination of the ground motions recorded in the near-source region resulting from the 22 February 2011 Christchurch earthquake. Particular attention is given to reconciling the observed spatial distribution of ground motions in terms of physical phenomena related to source, path and site effects. The large number of near-source observed strong ground motions show clear evidence of: forward-directivity, basin generated surface waves, liquefaction and other significant nonlinear site response. The pseudo-acceleration response spectra (SA) amplitudes and significant duration of strong motions agree well with empirical prediction models, except at long vibration periods where the influence of basin-generated surface waves and nonlinear site response are significant and not adequately accounted for in empirical SA models. Pseudo-acceleration response spectra are also compared with those observed in the 4 September 2010 Darfield earthquake and routine design response spectra used in order to emphasise the amplitude of ground shaking and elucidate the importance of local geotechnical characteristics on surface ground motions. The characteristics of the observed vertical component accelerations are shown to be strongly dependent on source-to-site distance and are comparable with those from the 4 September 2010 Darfield earthquake, implying the large amplitudes observed are simply a result of many observations at close distances rather than a peculiar source effect.

scholarly journals Free Field Surface Motion at Different Site Types due to Near-Fault Ground Motions

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Jagabandhu Dixit ◽  
D. M. Dewaikar ◽  
R. S. Jangid
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Free Field ◽  
Response Spectra ◽  
Response Analysis ◽  
Acceleration Response ◽  
Surface Motion ◽  
Near Fault ◽  
Acceleration Response Spectra ◽  
Site Category

Seismic hazards during many disastrous earthquakes are observed to be aggravating at the sites with the soft soil deposits due to amplification of ground motion. The characteristics of strong ground motion, the site category, depth of the soil column, type of rock strata, and the dynamic soil properties at a particular site significantly influence the free field motion during an earthquake. In this paper, free field surface motion is evaluated via seismic site response analysis that involves the propagation of earthquake ground motions from the bedrock through the overlying soil layers to the ground surface. These analyses are carried out for multiple near-fault seismic ground motions at 142 locations in Mumbai city categorized into different site classes. The free field surface motion is quantified in terms of amplification ratio, spectral relative velocity, and spectral acceleration. Seismic site coefficients at different time periods are also evaluated for each site category due to near-fault ground motions from the acceleration response spectra of free field surface motion at each site and the corresponding acceleration response spectra at a reference rock outcrop site.

Using Modified Mercalli Intensities to Estimate Acceleration Response Spectra for the 1906 San Francisco Earthquake

2006 ◽  
Vol 22 (2_suppl) ◽  
pp. 279-295 ◽  
Author(s):  
John Boatwright ◽  
Howard Bundock ◽  
Linda C. Seekins
Keyword(s):  
San Francisco ◽  
Strong Motion ◽  
Response Spectra ◽  
Peak Ground Velocity ◽  
San Jose ◽  
Acceleration Response ◽  
Loma Prieta Earthquake ◽  
Acceleration Response Spectra ◽  
Loma Prieta ◽  
The Difference

We derive and test relations between the Modified Mercalli Intensity (MMI) and the pseudo-acceleration response spectra at 1.0 and 0.3 s— SA(1.0 s) and SA(0.3 s)—in order to map response spectral ordinates for the 1906 San Francisco earthquake. Recent analyses of intensity have shown that MMI ≥ 6 correlates both with peak ground velocity and with response spectra for periods from 0.5 to 3.0 s. We use these recent results to derive a linear relation between MMI and log SA(1.0 s), and we refine this relation by comparing the SA(1.0 s) estimated from Boatwright and Bundock's (2005) MMI map for the 1906 earthquake to the SA(1.0 s) calculated from recordings of the 1989 Loma Prieta earthquake. South of San Jose, the intensity distributions for the 1906 and 1989 earthquakes are remarkably similar, despite the difference in magnitude and rupture extent between the two events. We use recent strong motion regressions to derive a relation between SA(1.0 s) and SA(0.3 s) for a M7.8 strike-slip earthquake that depends on soil type, acceleration level, and source distance. We test this relation by comparing SA(0.3 s) estimated for the 1906 earthquake to SA(0.3 s) calculated from recordings of both the 1989 Loma Prieta and 1994 Northridge earthquakes, as functions of distance from the fault.

Strong Motions on Land and Ocean Bottom: Comparison of Horizontal PGA, PGV, and 5% Damped Acceleration Response Spectra in Northeast Japan and the Japan Trench Area

2021 ◽  
Author(s):  
Yadab P. Dhakal ◽  
Takashi Kunugi ◽  
Wataru Suzuki ◽  
Takeshi Kimura ◽  
Nobuyuki Morikawa ◽  
...  
Keyword(s):  
Ground Motions ◽  
Response Spectra ◽  
Japan Trench ◽  
Ocean Bottom ◽  
Acceleration Response ◽  
Offshore Area ◽  
Acceleration Response Spectra ◽  
Short Period ◽  
Trench Area ◽  
Water Depths

ABSTRACT A large-scale permanent ocean-bottom seismograph network, named S-net, has been established in the Japan Trench area and consists of 150 observatories equipped with seismometers and tsunamimeters. Most stations at water depths <1500 m were buried to a depth of about 1 m while they were sited freely on the seafloors at greater water depths. To understand the characteristics of strong ground motions on the offshore area, we compared the horizontal vector peak ground accelerations (PGA), peak ground velocities (PGVs), and acceleration response spectra (ARS) between the land and S-net sites for nine earthquakes (5.3≤Mw≤7.1) using ground-motion prediction equations developed for Japan. We found that the observed values of PGAs and short-period (<0.5 s) ARS were generally similar between the land and S-net sites, whereas the PGVs and ARS for the periods longer than 0.5 s were apparently larger at the S-net sites. These results based on data covering a wide area on the seafloors were generally similar to the previous results based on limited ocean-bottom stations. However, analysis of the residuals, within the source-to-site distance of 200 km, revealed that the residual values were smaller in the shallow water region compared to those toward the Japan Trench, which is characterized by proximity to high Qs in the Pacific plate, the presence of thick unconsolidated sediments on the upper crust, and increasing heights of water columns. The difference of station settings in the shallow and deep water regions may also have contributed to the biased distribution of residuals at the short periods. Quantifications of these results are expected to contribute to the predictions of ground motions for earthquake early warning and seismic demand analysis of offshore facilities and await further analysis of a larger data set.

An Empirical Relationship between Fourier and Response Spectra Using Spectrum-Compatible Times Series

2017 ◽  
Vol 33 (1) ◽  
pp. 179-199 ◽  
Author(s):  
Luis A. Montejo ◽  
Aidcer L. Vidot-Vega
Keyword(s):  
Time Series ◽  
Earthquake Engineering ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Dependence ◽  
Empirical Relationship ◽  
Amplitude Spectrum ◽  
Strong Motion ◽  
Response Spectra ◽  
Elastic Response

The Fourier amplitude spectrum (FAS) is widely used in seismology and earthquake engineering as it provides valuable information regarding frequency dependent amplitude of the ground motion. However, for structural design and assessment, the preferred representation of seismic hazard continues to be based on the elastic response spectrum. Therefore, conversions between these spectra are often required. In this article, the connection between FAS and the 5% damping pseudo-acceleration response spectrum (5% PSA) is explored using large data sets of spectrum-compatible time series generated from white noise. The strong dependence of the relation between FAS and 5% PSA with strong motion duration is evidenced and a duration dependent empirical relationship between the both spectra is developed. The equation is validated using recorded ground motions and spectrum-compatible time series generated from the modification of these ground motions. The equation allows simpler one-step conversions when compared to iterative approaches based on RVT theory or time-consuming methodologies that require the generation of spectrum-compatible time series.

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