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.

Ground Motion Selection in the Near-Fault Region considering Directivity-Induced Pulse Effects

2019 ◽  
Vol 35 (2) ◽  
pp. 759-786 ◽  
Author(s):  
Karim Tarbali ◽  
Brendon A. Bradley ◽  
Jack W. Baker
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Seismic Hazard Analysis ◽  
Response Analysis ◽  
Seismic Demand ◽  
Ground Motion Selection ◽  
Near Fault ◽  
Fault Region

This paper focuses on the selection of ground motions for seismic response analysis in the near-fault region, where directivity effects are significant. An approach is presented to consider forward directivity velocity pulse effects in seismic hazard analysis without separate hazard calculations for ‘pulse-like’ and ‘non-pulse-like’ ground motions, resulting in a single target hazard (at the site of interest) for ground motion selection. The ability of ground motion selection methods to appropriately select records that exhibit pulse-like ground motions in the near-fault region is then examined. Applications for scenario and probabilistic seismic hazard analysis cases are examined through the computation of conditional seismic demand distributions and the seismic demand hazard. It is shown that ground motion selection based on an appropriate set of intensity measures (IMs) will lead to ground motion ensembles with an appropriate representation of the directivity-included target hazard in terms of IMs, which are themselves affected by directivity pulse effects. This alleviates the need to specify the proportion of pulse-like motions and their pulse periods a priori as strict criteria for ground motion selection.

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.

Effects of SSI on EPR™ In-Structure Response for a Rock Site: Coherent and Incoherent High Frequency Ground Motion

2010 ◽  
Author(s):  
James J. Johnson ◽  
Oliver Schneider ◽  
Werner Schuetz ◽  
Philippe Monette ◽  
Alejandro P. Asfura
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Ground Motions ◽  
Free Field ◽  
Response Spectra ◽  
Frequency Content ◽  
Structure Response ◽  
Standard Design ◽  
Rock Site ◽  
High Frequency Content

Recently, probabilistic seismic hazard assessments (PSHAs) performed for hard sites world-wide have yielded uniform hazard response spectra (UHRS) with significant high frequency content, i.e., frequency content greater than 10 Hz. This high frequency content is frequently due to near-field relatively low magnitude events. It is well known that these high frequency ground motions are not damaging to ductile structures, systems, and components (SSCs). One method of addressing the effect of these high frequency ground motions on structure response is to take into account the incoherency of ground motion. Over the past 25 years, free-field ground motion has been recorded providing an adequate basis for the development of ground motion coherency functions necessary to assess the effect of incoherence on nuclear power plant structures. The subject of this study was the AREVA NP EPR™ (European Power Reactor) nuclear island (NI) standard design. The effect of incoherency of ground motion on in-structure response spectra (ISRS) was assessed for the NI founded on a stiff rock site and subjected to high frequency enhanced input for hard rock sites. The ISRS at numerous locations and directions in the structures were calculated and compared. SSI is shown to be an important phenomenon for structures founded on stiff sites and subjected to high frequency ground motions.

Inelastic response spectra of self-centering structures with the flag-shaped hysteretic response subjected to near-fault pulse-type ground motions

2021 ◽  
pp. 875529302110003
Author(s):  
Huihui Dong ◽  
Qiang Han ◽  
Xiuli Du ◽  
Shoushan Cheng ◽  
Haifang He
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Displacement Velocity ◽  
Hysteretic Behavior ◽  
Hysteretic Model ◽  
Inelastic Response ◽  
Inelastic Displacement ◽  
Near Fault ◽  
Pulse Type

Many studies on the inelastic response spectra have mainly focused on structures with the conventional hysteretic behavior. However, for self-centering structures with the flag-shaped (FS) hysteretic behavior, the corresponding study is limited. The primary aim of this study is to investigate the inelastic response spectra of self-centering structures with FS hysteretic behavior subjected to the near-fault pulse-type ground motion. To this end, the smooth FS hysteretic model based on Bouc–Wen model is developed, and the characteristics of pulse-type ground motions are described in detail. It is found that the general features of inelastic response spectra of the FS model are sensitive to the acceleration-, velocity-, and displacement-sensitive spectral regions of the ground motion. The inelastic displacement, velocity, acceleration, and ductility factor spectra of the FS hysteretic model for pulse-type ground motions are much larger than those for ordinary ground motions, while the residual displacement spectra under the two types of ground motions are both very small due to its self-centering capacity. Moreover, the inelastic response spectra are affected by the ground motion characteristics and structural hysteresis behavior, especially the large pulse period and peak ground velocity (PGV) significantly increase the inelastic displacement, velocity, and acceleration spectra.

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.

NGA-West2 Ground Motion Model for the Average Horizontal Components of PGA, PGV, and 5% Damped Linear Acceleration Response Spectra

2014 ◽  
Vol 30 (3) ◽  
pp. 1087-1115 ◽  
Author(s):  
Kenneth W. Campbell ◽  
Yousef Bozorgnia
Keyword(s):  
Ground Motion ◽  
Hanging Wall ◽  
Linear Acceleration ◽  
Response Spectra ◽  
Prediction Equation ◽  
Acceleration Response ◽  
Small Magnitude ◽  
Anelastic Attenuation ◽  
Magnitude Scaling ◽  
Acceleration Response Spectra

We used an expanded PEER NGA-West2 database to develop a new ground motion prediction equation (GMPE) for the average horizontal components of PGA, PGV, and 5% damped linear pseudo-absolute acceleration response spectra at 21 periods ranging from 0.01 s to 10 s. In addition to those terms included in our now superseded 2008 GMPE, we include a more-detailed hanging wall model, scaling with hypocentral depth and fault dip, regionally independent geometric attenuation, regionally dependent anelastic attenuation and site conditions, and magnitude-dependent aleatory variability. The NGA-West2 database provides better constraints on magnitude scaling and attenuation of small-magnitude earthquakes, where our 2008 GMPE was known to be biased. We consider our new GMPE to be valid for estimating horizontal ground motion from shallow crustal continental earthquakes in an active tectonic domain for rupture distances ranging from 0 km to 300 km and magnitudes ranging from 3.3 to 7.5–8.5, depending on source mechanism.

Sign in / Sign up

Export Citation Format

Share Document