scholarly journals Attenuation of Energy-based Demand Parameters

2021 ◽  
Author(s):  
ALI SARI ◽  
Lance MANUEL
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Spectral Acceleration ◽  
Input Energy ◽  
Absorbed Energy ◽  
Energy Equivalent ◽  
Amplification Factors ◽  
Attenuation Model ◽  
Northwestern Turkey ◽  
Strength Based

Abstract The intensity of ground shaking and the demand on structures during earthquakes have been generally characterized using parameters such as peak ground acceleration as well as strength-based parameters such as response spectrum ordinates (e.g., spectral acceleration) that represent the maximum amplitude of shaking for structures with specified natural period and damping values. It has long been recognized that to assess the demands on structures during earthquakes, one might employ an energy-based approach (as an alternative to the more common strength-based one), especially when there is an interest in assessing damage potential of ground motions. An energy spectrum, obtained with the same level of effort required to construct a conventional response spectrum, is a convenient single-parameter description of both amplitude and duration of ground motion and can serve as a useful means by which to describe the performance of structures with different natural periods and damping ratios.In this study, attenuation models for Northwestern Turkey are developed for two parameters (defined herein) that are related to input energy and absorbed energy. The empirical models developed take advantage of the recent increase in the database on strong motion data for Northwestern Turkey. A total of 195 recordings from 17 recent seismic events are included in this database. The ground-motion prediction equations developed are for the geometric mean of the two horizontal components of the 5-percent damped energy parameters (elastic and inelastic input energy-equivalent acceleration, Ai, and absorbed energy-equivalent velocity, Aa) at various periods. Predictions of the energy-based parameters from the proposed attenuation model are compared with (strength-based) spectral acceleration levels predicted by Özbey et al [Soil Dyn. & Earthq. Eng., 24 (2004), pp. 115-125]. It is found that the energy demand parameters were generally greater with elastic Ai demands highest. In addition, the predicted energy-based parameter levels are compared with available Western U.S. attenuation model predictions for the same energy-based parameters. Western U.S. models predict similar energy demands to those with the proposed model. Finally, amplification factors for the energy-based parameters are proposed as a function of site class; these factors can be thought of as analogous to amplification factors for spectral acceleration as given in the NEHRP Seismic Provisions. The patterns related to the amplification are similar as with spectral acceleration in NEHRP (2001). A comparison of soil amplification effects for strength- and energy-based parameters is also discussed.

Amplification Factors for Equipment Design Subjected to Seismic Loading

1998 ◽  
Vol 120 (4) ◽  
pp. 334-342
Author(s):  
R. Jategaonkar ◽  
L. G. Jaeger
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Seismic Loading ◽  
Response Spectra ◽  
Structural Damping ◽  
Mathematical Technique ◽  
Ground Structure ◽  
Amplification Factors ◽  
Seismic Motion ◽  
Numerical Software

A mathematical technique is developed to evaluate the seismic response of primary equipment supported directly by the main structure and also the response of secondary equipment supported by the primary equipment. The method can be used for structures ranging from the simple to the complex, and is amenable to calculations based on standard spreadsheet or numerical software or, if desired, can be programmed. The technique can be used to develop amplification factors for seismic motion between ground, structure, and equipment. Alternatively, the method can be utilized to develop the ground response (or structure motion) spectra for various structural damping ratios and also floor response (or equipment response) spectra directly from a ground motion spectrum given as datum. The results are compared with the results from other well-established methods. The proposed method has an advantage over the other methods in that it enables direct computation of the third level response, i.e., response of the secondary equipment supported by the primary equipment; also, the method can be readily applied to any shape of ground motion response spectrum given as datum.

scholarly journals Checking the site categorization criteria and amplification factors of the 2021 draft of Eurocode 8 Part 1–1

2021 ◽  
Author(s):  
Roberto Paolucci ◽  
Mauro Aimar ◽  
Andrea Ciancimino ◽  
Marco Dotti ◽  
Sebastiano Foti ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Shear Wave ◽  
Ground Motion ◽  
Shear Wave Velocity ◽  
Soft Soil ◽  
Site Amplification ◽  
Soil Conditions ◽  
Eurocode 8 ◽  
Site Specific ◽  
Amplification Factors

AbstractIn this paper the site categorization criteria and the corresponding site amplification factors proposed in the 2021 draft of Part 1 of Eurocode 8 (2021-draft, CEN/TC250/SC8 Working Draft N1017) are first introduced and compared with the current version of Eurocode 8, as well as with site amplification factors from recent empirical ground motion prediction equations. Afterwards, these values are checked by two approaches. First, a wide dataset of strong motion records is built, where recording stations are classified according to 2021-draft, and the spectral amplifications are empirically estimated computing the site-to-site residuals from regional and global ground motion models for reference rock conditions. Second, a comprehensive parametric numerical study of one-dimensional (1D) site amplification is carried out, based on randomly generated shear-wave velocity profiles, classified according to the new criteria. A reasonably good agreement is found by both approaches. The most relevant discrepancies occur for the shallow soft soil conditions (soil category E) that, owing to the complex interaction of shear wave velocity, soil deposit thickness and frequency range of the excitation, show the largest scatter both in terms of records and of 1D numerical simulations. Furthermore, 1D numerical simulations for soft soil conditions tend to provide lower site amplification factors than 2021-draft, as well as lower than the corresponding site-to-site residuals from records, because of higher impact of non-linear (NL) site effects in the simulations. A site-specific study on NL effects at three KiK-net stations with a significantly large amount of high-intensity recorded ground motions gives support to the 2021-draft NL reduction factors, although the very limited number of recording stations allowing such analysis prevents deriving more general implications. In the presence of such controversial arguments, it is reasonable that a standard should adopt a prudent solution, with a limited reduction of the site amplification factors to account for NL soil response, while leaving the possibility to carry out site-specific estimations of such factors when sufficient information is available to model the ground strain dependency of local soil properties.

scholarly journals Simulation of response spectrum-compatible ground motions using wavelet-based multi-resolution analysis

2021 ◽  
pp. 002029402110130
Author(s):  
Guan Chen ◽  
Zhiren Zhu ◽  
Jun Hu
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Ground Motions ◽  
Power Spectra ◽  
Simulation Method ◽  
Eurocode 8 ◽  
Effective Response ◽  
Multi Resolution Analysis ◽  
Resolution Analysis ◽  
Simulated Ground Motions

This study proposed a simple and effective response spectrum-compatible ground motions simulation method to mitigate the scarcity of ground motions on seismic hazard analysis base on wavelet-based multi-resolution analysis. The feasibility of the proposed method is illustrated with two recorded ground motions in El Mayor-Cucapah earthquake. The results show that the proposed method enriches the ground motions exponentially. The simulated ground motions agree well with the attenuation characteristics of seismic ground motion without modulating process. Moreover, the pseudo-acceleration response spectrum error between the recorded ground motion and the average of the simulated ground motions is 5.2%, which fulfills the requirement prescribed in Eurocode 8 for artificially simulated ground motions. Besides, the cumulative power spectra between the simulated and recorded ground motions agree well on both high- and low-frequency regions. Therefore, the proposed method offers a feasible alternative in enriching response spectrum-compatible ground motions, especially on the regions with insufficient ground motions.

Directivity in NGA Earthquake Ground Motions: Analysis Using Isochrone Theory

2008 ◽  
Vol 24 (1) ◽  
pp. 279-298 ◽  
Author(s):  
Paul Spudich ◽  
Brian S. J. Chiou
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Strike Slip ◽  
Motion Prediction ◽  
Spectral Acceleration ◽  
Correction Factors ◽  
Ground Motion Prediction ◽  
Earthquake Ground Motions

We present correction factors that may be applied to the ground motion prediction relations of Abrahamson and Silva, Boore and Atkinson, Campbell and Bozorgnia, and Chiou and Youngs (all in this volume) to model the azimuthally varying distribution of the GMRotI50 component of ground motion (commonly called “directivity”) around earthquakes. Our correction factors may be used for planar or nonplanar faults having any dip or slip rake (faulting mechanism). Our correction factors predict directivity-induced variations of spectral acceleration that are roughly half of the strike-slip variations predicted by Somerville et. al. (1997), and use of our factors reduces record-to-record sigma by about 2–20% at 5 sec or greater period.

Distribution of ground-motion intensity inferred from questionnaire survey, earthquake recordings, and microtremor measurements—A case study in Christchurch, New Zealand, during the 1994 arthurs pass earthquake

1997 ◽  
Vol 87 (2) ◽  
pp. 356-369
Author(s):  
Takumi Toshinawa ◽  
J. John Taber ◽  
John B. Berrill
Keyword(s):  
New Zealand ◽  
Ground Motion ◽  
Intensity Data ◽  
Amplification Factors ◽  
Areal Distribution ◽  
Local Site ◽  
Geological Conditions ◽  
The City ◽  
Microtremor Measurements

Abstract The areal distribution of seismic ground-motion intensity in the city of Christchurch, New Zealand, during the 1994 Arthurs Pass Earthquake (ML 6.6) was evaluated using an intensity questionnaire together with local site amplifications inferred from seismic recordings and microtremors. In order to estimate the intensity in parts of the city where no intensity data were available, intensity data were compared to relative levels of shaking determined from both weak-motion and microtremor recordings. Weak ground-motion amplification factors were determined using ratios of ground accelerations at five sediment sites with respect to a rock site. Microtremor amplification factors were determined from horizontal-to-vertical spectral ratios at a 1-km spacing throughout the city. A positive correlation between weak-motion and microtremor amplification factors allowed extrapolation of microtremor amplification to estimated MM intensity (EMMI). EMMI ranged from 3 to 6 and was consistent with the questionnaire intensity and geological conditions and showed detailed information on the areal distribution of ground-motion intensity in the city.

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